diff --git a/.travis.yml b/.travis.yml
index 04516150..0bc3dc92 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -6,6 +6,7 @@ dist: trusty
 php:
   - 7.1
   - 7.2
+  - 7.3
   - nightly
 
 cache:
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8c033f93..1d6770e9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,7 +2,7 @@
 
   * Added ability to customize error handling at the Logger level using Logger::setExceptionHandler
   * Added InsightOpsHandler to migrate users of the LogEntriesHandler
-  * Added protection to NormalizerHandler against circular and very deep structures, it now stops normalizing at a depth of 9
+  * Added protection to NormalizerFormatter against circular and very deep structures, it now stops normalizing at a depth of 9
   * Added capture of stack traces to ErrorHandler when logging PHP errors
   * Added forwarding of context info to FluentdFormatter
   * Added SocketHandler::setChunkSize to override the default chunk size in case you must send large log lines to rsyslog for example
diff --git a/doc/04-extending.md b/doc/04-extending.md
index ffb07009..5ba7c0fd 100644
--- a/doc/04-extending.md
+++ b/doc/04-extending.md
@@ -30,13 +30,13 @@ class PDOHandler extends AbstractProcessingHandler
     private $pdo;
     private $statement;
 
-    public function __construct(PDO $pdo, $level = Logger::DEBUG, $bubble = true)
+    public function __construct(PDO $pdo, $level = Logger::DEBUG, bool $bubble = true)
     {
         $this->pdo = $pdo;
         parent::__construct($level, $bubble);
     }
 
-    protected function write(array $record)
+    protected function write(array $record): void
     {
         if (!$this->initialized) {
             $this->initialize();
diff --git a/src/Monolog/DateTimeImmutable.php b/src/Monolog/DateTimeImmutable.php
index 6e7a5fc6..6a1ba9b2 100644
--- a/src/Monolog/DateTimeImmutable.php
+++ b/src/Monolog/DateTimeImmutable.php
@@ -11,6 +11,8 @@
 
 namespace Monolog;
 
+use DateTimeZone;
+
 /**
  * Overrides default json encoding of date time objects
  *
@@ -19,9 +21,12 @@ namespace Monolog;
  */
 class DateTimeImmutable extends \DateTimeImmutable implements \JsonSerializable
 {
+    /**
+     * @var bool
+     */
     private $useMicroseconds;
 
-    public function __construct($useMicroseconds, \DateTimeZone $timezone = null)
+    public function __construct(bool $useMicroseconds, ?DateTimeZone $timezone = null)
     {
         $this->useMicroseconds = $useMicroseconds;
 
diff --git a/src/Monolog/Formatter/GelfMessageFormatter.php b/src/Monolog/Formatter/GelfMessageFormatter.php
index 4e95a6e4..21176a64 100644
--- a/src/Monolog/Formatter/GelfMessageFormatter.php
+++ b/src/Monolog/Formatter/GelfMessageFormatter.php
@@ -58,13 +58,13 @@ class GelfMessageFormatter extends NormalizerFormatter
         Logger::EMERGENCY => 0,
     ];
 
-    public function __construct(string $systemName = null, string $extraPrefix = null, string $contextPrefix = 'ctxt_', int $maxLength = null)
+    public function __construct(?string $systemName = null, ?string $extraPrefix = null, string $contextPrefix = 'ctxt_', ?int $maxLength = null)
     {
         parent::__construct('U.u');
 
-        $this->systemName = $systemName ?: gethostname();
+        $this->systemName = (is_null($systemName) || $systemName === '') ? gethostname() : $systemName;
 
-        $this->extraPrefix = $extraPrefix;
+        $this->extraPrefix = is_null($extraPrefix) ? '' : $extraPrefix;
         $this->contextPrefix = $contextPrefix;
         $this->maxLength = is_null($maxLength) ? self::DEFAULT_MAX_LENGTH : $maxLength;
     }
diff --git a/src/Monolog/Formatter/HtmlFormatter.php b/src/Monolog/Formatter/HtmlFormatter.php
index 26f74fa9..0f8db9a7 100644
--- a/src/Monolog/Formatter/HtmlFormatter.php
+++ b/src/Monolog/Formatter/HtmlFormatter.php
@@ -37,9 +37,9 @@ class HtmlFormatter extends NormalizerFormatter
     ];
 
     /**
-     * @param string $dateFormat The format of the timestamp: one supported by DateTime::format
+     * @param ?string $dateFormat The format of the timestamp: one supported by DateTime::format
      */
-    public function __construct(string $dateFormat = null)
+    public function __construct(?string $dateFormat = null)
     {
         parent::__construct($dateFormat);
     }
@@ -47,10 +47,9 @@ class HtmlFormatter extends NormalizerFormatter
     /**
      * Creates an HTML table row
      *
-     * @param  string $th       Row header content
-     * @param  string $td       Row standard cell content
-     * @param  bool   $escapeTd false if td content must not be html escaped
-     * @return string
+     * @param string $th       Row header content
+     * @param string $td       Row standard cell content
+     * @param bool   $escapeTd false if td content must not be html escaped
      */
     protected function addRow(string $th, string $td = ' ', bool $escapeTd = true): string
     {
@@ -79,8 +78,8 @@ class HtmlFormatter extends NormalizerFormatter
     /**
      * Formats a log record.
      *
-     * @param  array $record A record to format
-     * @return mixed The formatted record
+     * @param  array  $record A record to format
+     * @return string The formatted record
      */
     public function format(array $record): string
     {
@@ -113,8 +112,8 @@ class HtmlFormatter extends NormalizerFormatter
     /**
      * Formats a set of log records.
      *
-     * @param  array $records A set of records to format
-     * @return mixed The formatted set of records
+     * @param  array  $records A set of records to format
+     * @return string The formatted set of records
      */
     public function formatBatch(array $records): string
     {
diff --git a/src/Monolog/Formatter/JsonFormatter.php b/src/Monolog/Formatter/JsonFormatter.php
index e0d5449e..3281be12 100644
--- a/src/Monolog/Formatter/JsonFormatter.php
+++ b/src/Monolog/Formatter/JsonFormatter.php
@@ -61,6 +61,8 @@ class JsonFormatter extends NormalizerFormatter
 
     /**
      * {@inheritdoc}
+     *
+     * @suppress PhanTypeComparisonToArray
      */
     public function format(array $record): string
     {
diff --git a/src/Monolog/Formatter/LineFormatter.php b/src/Monolog/Formatter/LineFormatter.php
index 6cbdb520..48bb2c05 100644
--- a/src/Monolog/Formatter/LineFormatter.php
+++ b/src/Monolog/Formatter/LineFormatter.php
@@ -29,14 +29,14 @@ class LineFormatter extends NormalizerFormatter
     protected $includeStacktraces;
 
     /**
-     * @param string $format                     The format of the message
-     * @param string $dateFormat                 The format of the timestamp: one supported by DateTime::format
-     * @param bool   $allowInlineLineBreaks      Whether to allow inline line breaks in log entries
-     * @param bool   $ignoreEmptyContextAndExtra
+     * @param ?string $format                     The format of the message
+     * @param ?string $dateFormat                 The format of the timestamp: one supported by DateTime::format
+     * @param bool    $allowInlineLineBreaks      Whether to allow inline line breaks in log entries
+     * @param bool    $ignoreEmptyContextAndExtra
      */
-    public function __construct(string $format = null, string $dateFormat = null, bool $allowInlineLineBreaks = false, bool $ignoreEmptyContextAndExtra = false)
+    public function __construct(?string $format = null, ?string $dateFormat = null, bool $allowInlineLineBreaks = false, bool $ignoreEmptyContextAndExtra = false)
     {
-        $this->format = $format ?: static::SIMPLE_FORMAT;
+        $this->format = $format === null ? static::SIMPLE_FORMAT : $format;
         $this->allowInlineLineBreaks = $allowInlineLineBreaks;
         $this->ignoreEmptyContextAndExtra = $ignoreEmptyContextAndExtra;
         parent::__construct($dateFormat);
@@ -124,6 +124,9 @@ class LineFormatter extends NormalizerFormatter
         return $this->replaceNewlines($this->convertToString($value));
     }
 
+    /**
+     * @suppress PhanParamSignatureMismatch
+     */
     protected function normalizeException(\Throwable $e, int $depth = 0): string
     {
         $str = $this->formatException($e);
diff --git a/src/Monolog/Formatter/LogmaticFormatter.php b/src/Monolog/Formatter/LogmaticFormatter.php
index 7a75e00f..8c6ff2f4 100644
--- a/src/Monolog/Formatter/LogmaticFormatter.php
+++ b/src/Monolog/Formatter/LogmaticFormatter.php
@@ -21,30 +21,20 @@ class LogmaticFormatter extends JsonFormatter
     const MARKERS = ["sourcecode", "php"];
 
     /**
-     * @param string
+     * @var string
      */
     protected $hostname = '';
 
     /**
-     * @param string
+     * @var string
      */
     protected $appname = '';
 
-    /**
-     * Set hostname
-     *
-     * @param string $hostname
-     */
     public function setHostname(string $hostname)
     {
         $this->hostname = $hostname;
     }
 
-    /**
-     * Set appname
-     *
-     * @param string $appname
-     */
     public function setAppname(string $appname)
     {
         $this->appname = $appname;
diff --git a/src/Monolog/Formatter/LogstashFormatter.php b/src/Monolog/Formatter/LogstashFormatter.php
index 74464e57..6404acf0 100644
--- a/src/Monolog/Formatter/LogstashFormatter.php
+++ b/src/Monolog/Formatter/LogstashFormatter.php
@@ -42,17 +42,17 @@ class LogstashFormatter extends NormalizerFormatter
     protected $contextKey;
 
     /**
-     * @param string $applicationName the application that sends the data, used as the "type" field of logstash
-     * @param string $systemName      the system/machine name, used as the "source" field of logstash, defaults to the hostname of the machine
-     * @param string $extraKey        the key for extra keys inside logstash "fields", defaults to extra
-     * @param string $contextKey      the key for context keys inside logstash "fields", defaults to context
+     * @param string  $applicationName the application that sends the data, used as the "type" field of logstash
+     * @param ?string $systemName      the system/machine name, used as the "source" field of logstash, defaults to the hostname of the machine
+     * @param string  $extraKey        the key for extra keys inside logstash "fields", defaults to extra
+     * @param string  $contextKey      the key for context keys inside logstash "fields", defaults to context
      */
-    public function __construct(string $applicationName, string $systemName = null, string $extraKey = 'extra', string $contextKey = 'context')
+    public function __construct(string $applicationName, ?string $systemName = null, string $extraKey = 'extra', string $contextKey = 'context')
     {
         // logstash requires a ISO 8601 format date with optional millisecond precision.
         parent::__construct('Y-m-d\TH:i:s.uP');
 
-        $this->systemName = $systemName ?: gethostname();
+        $this->systemName = $systemName === null ? gethostname() : $systemName;
         $this->applicationName = $applicationName;
         $this->extraKey = $extraKey;
         $this->contextKey = $contextKey;
diff --git a/src/Monolog/Formatter/NormalizerFormatter.php b/src/Monolog/Formatter/NormalizerFormatter.php
index 2177f91e..c325865b 100644
--- a/src/Monolog/Formatter/NormalizerFormatter.php
+++ b/src/Monolog/Formatter/NormalizerFormatter.php
@@ -28,9 +28,9 @@ class NormalizerFormatter implements FormatterInterface
     protected $maxNormalizeItemCount = 1000;
 
     /**
-     * @param string $dateFormat The format of the timestamp: one supported by DateTime::format
+     * @param ?string $dateFormat The format of the timestamp: one supported by DateTime::format
      */
-    public function __construct(string $dateFormat = null)
+    public function __construct(?string $dateFormat = null)
     {
         $this->dateFormat = null === $dateFormat ? static::SIMPLE_DATE : $dateFormat;
         if (!function_exists('json_encode')) {
diff --git a/src/Monolog/Formatter/WildfireFormatter.php b/src/Monolog/Formatter/WildfireFormatter.php
index c8a3bb4a..a5812b89 100644
--- a/src/Monolog/Formatter/WildfireFormatter.php
+++ b/src/Monolog/Formatter/WildfireFormatter.php
@@ -91,7 +91,7 @@ class WildfireFormatter extends NormalizerFormatter
 
         // The message itself is a serialization of the above JSON object + it's length
         return sprintf(
-            '%s|%s|',
+            '%d|%s|',
             strlen($json),
             $json
         );
@@ -107,6 +107,7 @@ class WildfireFormatter extends NormalizerFormatter
 
     /**
      * {@inheritdoc}
+     * @suppress PhanTypeMismatchReturn
      */
     protected function normalize($data, int $depth = 0)
     {
diff --git a/src/Monolog/Handler/AbstractHandler.php b/src/Monolog/Handler/AbstractHandler.php
index d4771084..7c507466 100644
--- a/src/Monolog/Handler/AbstractHandler.php
+++ b/src/Monolog/Handler/AbstractHandler.php
@@ -27,7 +27,7 @@ abstract class AbstractHandler extends Handler
      * @param int|string $level  The minimum logging level at which this handler will be triggered
      * @param bool       $bubble Whether the messages that are handled can bubble up the stack or not
      */
-    public function __construct($level = Logger::DEBUG, $bubble = true)
+    public function __construct($level = Logger::DEBUG, bool $bubble = true)
     {
         $this->setLevel($level);
         $this->bubble = $bubble;
diff --git a/src/Monolog/Handler/AbstractProcessingHandler.php b/src/Monolog/Handler/AbstractProcessingHandler.php
index 654e6718..474c4860 100644
--- a/src/Monolog/Handler/AbstractProcessingHandler.php
+++ b/src/Monolog/Handler/AbstractProcessingHandler.php
@@ -46,9 +46,6 @@ abstract class AbstractProcessingHandler extends AbstractHandler implements Proc
 
     /**
      * Writes the record down to the log of the implementing handler
-     *
-     * @param  array $record
-     * @return void
      */
-    abstract protected function write(array $record);
+    abstract protected function write(array $record): void;
 }
diff --git a/src/Monolog/Handler/AbstractSyslogHandler.php b/src/Monolog/Handler/AbstractSyslogHandler.php
index 0c692aa9..9a9b5238 100644
--- a/src/Monolog/Handler/AbstractSyslogHandler.php
+++ b/src/Monolog/Handler/AbstractSyslogHandler.php
@@ -54,11 +54,11 @@ abstract class AbstractSyslogHandler extends AbstractProcessingHandler
     ];
 
     /**
-     * @param mixed $facility
-     * @param int   $level    The minimum logging level at which this handler will be triggered
-     * @param bool  $bubble   Whether the messages that are handled can bubble up the stack or not
+     * @param mixed      $facility
+     * @param string|int $level    The minimum logging level at which this handler will be triggered
+     * @param bool       $bubble   Whether the messages that are handled can bubble up the stack or not
      */
-    public function __construct($facility = LOG_USER, $level = Logger::DEBUG, $bubble = true)
+    public function __construct($facility = LOG_USER, $level = Logger::DEBUG, bool $bubble = true)
     {
         parent::__construct($level, $bubble);
 
diff --git a/src/Monolog/Handler/AmqpHandler.php b/src/Monolog/Handler/AmqpHandler.php
index 6e39a113..ba45dd51 100644
--- a/src/Monolog/Handler/AmqpHandler.php
+++ b/src/Monolog/Handler/AmqpHandler.php
@@ -33,10 +33,10 @@ class AmqpHandler extends AbstractProcessingHandler
     /**
      * @param AMQPExchange|AMQPChannel $exchange     AMQPExchange (php AMQP ext) or PHP AMQP lib channel, ready for use
      * @param string                   $exchangeName Optional exchange name, for AMQPChannel (PhpAmqpLib) only
-     * @param int                      $level
+     * @param string|int               $level        The minimum logging level at which this handler will be triggered
      * @param bool                     $bubble       Whether the messages that are handled can bubble up the stack or not
      */
-    public function __construct($exchange, $exchangeName = null, $level = Logger::DEBUG, $bubble = true)
+    public function __construct($exchange, ?string $exchangeName = null, $level = Logger::DEBUG, bool $bubble = true)
     {
         if ($exchange instanceof AMQPChannel) {
             $this->exchangeName = $exchangeName;
@@ -53,7 +53,7 @@ class AmqpHandler extends AbstractProcessingHandler
     /**
      * {@inheritDoc}
      */
-    protected function write(array $record)
+    protected function write(array $record): void
     {
         $data = $record["formatted"];
         $routingKey = $this->getRoutingKey($record);
@@ -80,7 +80,7 @@ class AmqpHandler extends AbstractProcessingHandler
     /**
      * {@inheritDoc}
      */
-    public function handleBatch(array $records)
+    public function handleBatch(array $records): void
     {
         if ($this->exchange instanceof AMQPExchange) {
             parent::handleBatch($records);
@@ -108,25 +108,18 @@ class AmqpHandler extends AbstractProcessingHandler
 
     /**
      * Gets the routing key for the AMQP exchange
-     *
-     * @param  array  $record
-     * @return string
      */
-    protected function getRoutingKey(array $record)
+    protected function getRoutingKey(array $record): string
     {
         $routingKey = sprintf('%s.%s', $record['level_name'], $record['channel']);
 
         return strtolower($routingKey);
     }
 
-    /**
-     * @param  string      $data
-     * @return AMQPMessage
-     */
-    private function createAmqpMessage($data)
+    private function createAmqpMessage(string $data): AMQPMessage
     {
         return new AMQPMessage(
-            (string) $data,
+            $data,
             [
                 'delivery_mode' => 2,
                 'content_type' => 'application/json',
diff --git a/src/Monolog/Handler/BrowserConsoleHandler.php b/src/Monolog/Handler/BrowserConsoleHandler.php
index 7774adef..37a66d62 100755
--- a/src/Monolog/Handler/BrowserConsoleHandler.php
+++ b/src/Monolog/Handler/BrowserConsoleHandler.php
@@ -41,7 +41,7 @@ class BrowserConsoleHandler extends AbstractProcessingHandler
     /**
      * {@inheritDoc}
      */
-    protected function write(array $record)
+    protected function write(array $record): void
     {
         // Accumulate records
         static::$records[] = $record;
diff --git a/src/Monolog/Handler/BufferHandler.php b/src/Monolog/Handler/BufferHandler.php
index 676c7c14..a8a64394 100644
--- a/src/Monolog/Handler/BufferHandler.php
+++ b/src/Monolog/Handler/BufferHandler.php
@@ -39,7 +39,7 @@ class BufferHandler extends AbstractHandler implements ProcessableHandlerInterfa
      * @param bool             $bubble          Whether the messages that are handled can bubble up the stack or not
      * @param bool             $flushOnOverflow If true, the buffer is flushed when the max size has been reached, by default oldest entries are discarded
      */
-    public function __construct(HandlerInterface $handler, $bufferLimit = 0, $level = Logger::DEBUG, $bubble = true, $flushOnOverflow = false)
+    public function __construct(HandlerInterface $handler, $bufferLimit = 0, $level = Logger::DEBUG, bool $bubble = true, $flushOnOverflow = false)
     {
         parent::__construct($level, $bubble);
         $this->handler = $handler;
@@ -101,7 +101,7 @@ class BufferHandler extends AbstractHandler implements ProcessableHandlerInterfa
     /**
      * {@inheritdoc}
      */
-    public function close()
+    public function close(): void
     {
         $this->flush();
     }
diff --git a/src/Monolog/Handler/ChromePHPHandler.php b/src/Monolog/Handler/ChromePHPHandler.php
index 9c1ca523..46ef7d34 100644
--- a/src/Monolog/Handler/ChromePHPHandler.php
+++ b/src/Monolog/Handler/ChromePHPHandler.php
@@ -64,7 +64,7 @@ class ChromePHPHandler extends AbstractProcessingHandler
      * @param int  $level  The minimum logging level at which this handler will be triggered
      * @param bool $bubble Whether the messages that are handled can bubble up the stack or not
      */
-    public function __construct($level = Logger::DEBUG, $bubble = true)
+    public function __construct($level = Logger::DEBUG, bool $bubble = true)
     {
         parent::__construct($level, $bubble);
         if (!function_exists('json_encode')) {
@@ -75,7 +75,7 @@ class ChromePHPHandler extends AbstractProcessingHandler
     /**
      * {@inheritdoc}
      */
-    public function handleBatch(array $records)
+    public function handleBatch(array $records): void
     {
         if (!$this->isWebRequest()) {
             return;
@@ -112,7 +112,7 @@ class ChromePHPHandler extends AbstractProcessingHandler
      * @see send()
      * @param array $record
      */
-    protected function write(array $record)
+    protected function write(array $record): void
     {
         if (!$this->isWebRequest()) {
             return;
diff --git a/src/Monolog/Handler/CouchDBHandler.php b/src/Monolog/Handler/CouchDBHandler.php
index e0603f34..b2d1e189 100644
--- a/src/Monolog/Handler/CouchDBHandler.php
+++ b/src/Monolog/Handler/CouchDBHandler.php
@@ -24,7 +24,7 @@ class CouchDBHandler extends AbstractProcessingHandler
 {
     private $options;
 
-    public function __construct(array $options = [], $level = Logger::DEBUG, $bubble = true)
+    public function __construct(array $options = [], $level = Logger::DEBUG, bool $bubble = true)
     {
         $this->options = array_merge([
             'host'     => 'localhost',
@@ -40,7 +40,7 @@ class CouchDBHandler extends AbstractProcessingHandler
     /**
      * {@inheritDoc}
      */
-    protected function write(array $record)
+    protected function write(array $record): void
     {
         $basicAuth = null;
         if ($this->options['username']) {
diff --git a/src/Monolog/Handler/CubeHandler.php b/src/Monolog/Handler/CubeHandler.php
index 82b16921..7de7705a 100644
--- a/src/Monolog/Handler/CubeHandler.php
+++ b/src/Monolog/Handler/CubeHandler.php
@@ -35,7 +35,7 @@ class CubeHandler extends AbstractProcessingHandler
      *                                   A valid url must consist of three parts : protocol://host:port
      *                                   Only valid protocols used by Cube are http and udp
      */
-    public function __construct($url, $level = Logger::DEBUG, $bubble = true)
+    public function __construct($url, $level = Logger::DEBUG, bool $bubble = true)
     {
         $urlInfo = parse_url($url);
 
@@ -102,7 +102,7 @@ class CubeHandler extends AbstractProcessingHandler
     /**
      * {@inheritdoc}
      */
-    protected function write(array $record)
+    protected function write(array $record): void
     {
         $date = $record['datetime'];
 
diff --git a/src/Monolog/Handler/Curl/Util.php b/src/Monolog/Handler/Curl/Util.php
index b0bec3d9..f1d0c17d 100644
--- a/src/Monolog/Handler/Curl/Util.php
+++ b/src/Monolog/Handler/Curl/Util.php
@@ -29,7 +29,7 @@ class Util
      * @param  resource          $ch curl handler
      * @throws \RuntimeException
      */
-    public static function execute($ch, $retries = 5, $closeAfterDone = true)
+    public static function execute($ch, int $retries = 5, bool $closeAfterDone = true): void
     {
         while ($retries--) {
             if (curl_exec($ch) === false) {
@@ -42,7 +42,7 @@ class Util
                         curl_close($ch);
                     }
 
-                    throw new \RuntimeException(sprintf('Curl error (code %s): %s', $curlErrno, $curlError));
+                    throw new \RuntimeException(sprintf('Curl error (code %d): %s', $curlErrno, $curlError));
                 }
 
                 continue;
diff --git a/src/Monolog/Handler/DeduplicationHandler.php b/src/Monolog/Handler/DeduplicationHandler.php
index 6d7753cb..ce4b99e2 100644
--- a/src/Monolog/Handler/DeduplicationHandler.php
+++ b/src/Monolog/Handler/DeduplicationHandler.php
@@ -62,7 +62,7 @@ class DeduplicationHandler extends BufferHandler
      * @param int              $time               The period (in seconds) during which duplicate entries should be suppressed after a given log is sent through
      * @param bool             $bubble             Whether the messages that are handled can bubble up the stack or not
      */
-    public function __construct(HandlerInterface $handler, $deduplicationStore = null, $deduplicationLevel = Logger::ERROR, $time = 60, $bubble = true)
+    public function __construct(HandlerInterface $handler, $deduplicationStore = null, $deduplicationLevel = Logger::ERROR, $time = 60, bool $bubble = true)
     {
         parent::__construct($handler, 0, Logger::DEBUG, $bubble, false);
 
diff --git a/src/Monolog/Handler/DoctrineCouchDBHandler.php b/src/Monolog/Handler/DoctrineCouchDBHandler.php
index 13a08eec..b80490d1 100644
--- a/src/Monolog/Handler/DoctrineCouchDBHandler.php
+++ b/src/Monolog/Handler/DoctrineCouchDBHandler.php
@@ -25,7 +25,7 @@ class DoctrineCouchDBHandler extends AbstractProcessingHandler
 {
     private $client;
 
-    public function __construct(CouchDBClient $client, $level = Logger::DEBUG, $bubble = true)
+    public function __construct(CouchDBClient $client, $level = Logger::DEBUG, bool $bubble = true)
     {
         $this->client = $client;
         parent::__construct($level, $bubble);
@@ -34,7 +34,7 @@ class DoctrineCouchDBHandler extends AbstractProcessingHandler
     /**
      * {@inheritDoc}
      */
-    protected function write(array $record)
+    protected function write(array $record): void
     {
         $this->client->postDocument($record['formatted']);
     }
diff --git a/src/Monolog/Handler/DynamoDbHandler.php b/src/Monolog/Handler/DynamoDbHandler.php
index a6991fa9..cd2bc64a 100644
--- a/src/Monolog/Handler/DynamoDbHandler.php
+++ b/src/Monolog/Handler/DynamoDbHandler.php
@@ -54,7 +54,7 @@ class DynamoDbHandler extends AbstractProcessingHandler
      * @param int            $level
      * @param bool           $bubble
      */
-    public function __construct(DynamoDbClient $client, $table, $level = Logger::DEBUG, $bubble = true)
+    public function __construct(DynamoDbClient $client, $table, $level = Logger::DEBUG, bool $bubble = true)
     {
         if (defined('Aws\Sdk::VERSION') && version_compare(Sdk::VERSION, '3.0', '>=')) {
             $this->version = 3;
@@ -72,7 +72,7 @@ class DynamoDbHandler extends AbstractProcessingHandler
     /**
      * {@inheritdoc}
      */
-    protected function write(array $record)
+    protected function write(array $record): void
     {
         $filtered = $this->filterEmptyFields($record['formatted']);
         if ($this->version === 3) {
diff --git a/src/Monolog/Handler/ElasticSearchHandler.php b/src/Monolog/Handler/ElasticSearchHandler.php
index b7dc5676..619e84dc 100644
--- a/src/Monolog/Handler/ElasticSearchHandler.php
+++ b/src/Monolog/Handler/ElasticSearchHandler.php
@@ -51,7 +51,7 @@ class ElasticSearchHandler extends AbstractProcessingHandler
      * @param int    $level   The minimum logging level at which this handler will be triggered
      * @param bool   $bubble  Whether the messages that are handled can bubble up the stack or not
      */
-    public function __construct(Client $client, array $options = [], $level = Logger::DEBUG, $bubble = true)
+    public function __construct(Client $client, array $options = [], $level = Logger::DEBUG, bool $bubble = true)
     {
         parent::__construct($level, $bubble);
         $this->client = $client;
@@ -68,7 +68,7 @@ class ElasticSearchHandler extends AbstractProcessingHandler
     /**
      * {@inheritDoc}
      */
-    protected function write(array $record)
+    protected function write(array $record): void
     {
         $this->bulkSend([$record['formatted']]);
     }
@@ -105,7 +105,7 @@ class ElasticSearchHandler extends AbstractProcessingHandler
     /**
      * {@inheritdoc}
      */
-    public function handleBatch(array $records)
+    public function handleBatch(array $records): void
     {
         $documents = $this->getFormatter()->formatBatch($records);
         $this->bulkSend($documents);
diff --git a/src/Monolog/Handler/ErrorLogHandler.php b/src/Monolog/Handler/ErrorLogHandler.php
index 3108aed7..60f12d11 100644
--- a/src/Monolog/Handler/ErrorLogHandler.php
+++ b/src/Monolog/Handler/ErrorLogHandler.php
@@ -34,7 +34,7 @@ class ErrorLogHandler extends AbstractProcessingHandler
      * @param bool $bubble         Whether the messages that are handled can bubble up the stack or not
      * @param bool $expandNewlines If set to true, newlines in the message will be expanded to be take multiple log entries
      */
-    public function __construct($messageType = self::OPERATING_SYSTEM, $level = Logger::DEBUG, $bubble = true, $expandNewlines = false)
+    public function __construct($messageType = self::OPERATING_SYSTEM, $level = Logger::DEBUG, bool $bubble = true, $expandNewlines = false)
     {
         parent::__construct($level, $bubble);
 
@@ -70,7 +70,7 @@ class ErrorLogHandler extends AbstractProcessingHandler
     /**
      * {@inheritdoc}
      */
-    protected function write(array $record)
+    protected function write(array $record): void
     {
         if (!$this->expandNewlines) {
             error_log((string) $record['formatted'], $this->messageType);
diff --git a/src/Monolog/Handler/FilterHandler.php b/src/Monolog/Handler/FilterHandler.php
index b42ce966..886178de 100644
--- a/src/Monolog/Handler/FilterHandler.php
+++ b/src/Monolog/Handler/FilterHandler.php
@@ -52,7 +52,7 @@ class FilterHandler extends Handler implements ProcessableHandlerInterface
      * @param int                       $maxLevel       Maximum level to accept, only used if $minLevelOrList is not an array
      * @param bool                      $bubble         Whether the messages that are handled can bubble up the stack or not
      */
-    public function __construct($handler, $minLevelOrList = Logger::DEBUG, $maxLevel = Logger::EMERGENCY, $bubble = true)
+    public function __construct($handler, $minLevelOrList = Logger::DEBUG, $maxLevel = Logger::EMERGENCY, bool $bubble = true)
     {
         $this->handler  = $handler;
         $this->bubble   = $bubble;
@@ -126,7 +126,7 @@ class FilterHandler extends Handler implements ProcessableHandlerInterface
     /**
      * {@inheritdoc}
      */
-    public function handleBatch(array $records)
+    public function handleBatch(array $records): void
     {
         $filtered = [];
         foreach ($records as $record) {
diff --git a/src/Monolog/Handler/FingersCrossed/ActivationStrategyInterface.php b/src/Monolog/Handler/FingersCrossed/ActivationStrategyInterface.php
index 3b765969..1ba99c73 100644
--- a/src/Monolog/Handler/FingersCrossed/ActivationStrategyInterface.php
+++ b/src/Monolog/Handler/FingersCrossed/ActivationStrategyInterface.php
@@ -20,9 +20,6 @@ interface ActivationStrategyInterface
 {
     /**
      * Returns whether the given record activates the handler.
-     *
-     * @param  array $record
-     * @return bool
      */
     public function isHandlerActivated(array $record): bool;
 }
diff --git a/src/Monolog/Handler/FingersCrossed/ChannelLevelActivationStrategy.php b/src/Monolog/Handler/FingersCrossed/ChannelLevelActivationStrategy.php
index 31e06a27..f98ecfac 100644
--- a/src/Monolog/Handler/FingersCrossed/ChannelLevelActivationStrategy.php
+++ b/src/Monolog/Handler/FingersCrossed/ChannelLevelActivationStrategy.php
@@ -46,7 +46,7 @@ class ChannelLevelActivationStrategy implements ActivationStrategyInterface
     private $channelToActionLevel;
 
     /**
-     * @param string|int $defaultActionLevel   The default action level to be used if the record's category doesn't match any
+     * @param int|string $defaultActionLevel   The default action level to be used if the record's category doesn't match any
      * @param array      $channelToActionLevel An array that maps channel names to action levels.
      */
     public function __construct($defaultActionLevel, array $channelToActionLevel = [])
diff --git a/src/Monolog/Handler/FingersCrossed/ErrorLevelActivationStrategy.php b/src/Monolog/Handler/FingersCrossed/ErrorLevelActivationStrategy.php
index 54132b20..71601e40 100644
--- a/src/Monolog/Handler/FingersCrossed/ErrorLevelActivationStrategy.php
+++ b/src/Monolog/Handler/FingersCrossed/ErrorLevelActivationStrategy.php
@@ -26,7 +26,7 @@ class ErrorLevelActivationStrategy implements ActivationStrategyInterface
     private $actionLevel;
 
     /**
-     * @param string|int $actionLevel
+     * @param int|string $actionLevel Level or name or value
      */
     public function __construct($actionLevel)
     {
diff --git a/src/Monolog/Handler/FingersCrossedHandler.php b/src/Monolog/Handler/FingersCrossedHandler.php
index 8943d4f0..8e33f253 100644
--- a/src/Monolog/Handler/FingersCrossedHandler.php
+++ b/src/Monolog/Handler/FingersCrossedHandler.php
@@ -47,7 +47,7 @@ class FingersCrossedHandler extends Handler implements ProcessableHandlerInterfa
      * @param bool                            $stopBuffering      Whether the handler should stop buffering after being triggered (default true)
      * @param int                             $passthruLevel      Minimum level to always flush to handler on close, even if strategy not triggered
      */
-    public function __construct($handler, $activationStrategy = null, $bufferSize = 0, $bubble = true, $stopBuffering = true, $passthruLevel = null)
+    public function __construct($handler, $activationStrategy = null, $bufferSize = 0, bool $bubble = true, $stopBuffering = true, $passthruLevel = null)
     {
         if (null === $activationStrategy) {
             $activationStrategy = new ErrorLevelActivationStrategy(Logger::WARNING);
@@ -128,7 +128,7 @@ class FingersCrossedHandler extends Handler implements ProcessableHandlerInterfa
     /**
      * {@inheritdoc}
      */
-    public function close()
+    public function close(): void
     {
         if (null !== $this->passthruLevel) {
             $level = $this->passthruLevel;
diff --git a/src/Monolog/Handler/FirePHPHandler.php b/src/Monolog/Handler/FirePHPHandler.php
index 8f5c0c69..29b4714d 100644
--- a/src/Monolog/Handler/FirePHPHandler.php
+++ b/src/Monolog/Handler/FirePHPHandler.php
@@ -130,7 +130,7 @@ class FirePHPHandler extends AbstractProcessingHandler
      * @see sendInitHeaders()
      * @param array $record
      */
-    protected function write(array $record)
+    protected function write(array $record): void
     {
         if (!self::$sendHeaders || !$this->isWebRequest()) {
             return;
diff --git a/src/Monolog/Handler/FleepHookHandler.php b/src/Monolog/Handler/FleepHookHandler.php
index 748100b1..2740b883 100644
--- a/src/Monolog/Handler/FleepHookHandler.php
+++ b/src/Monolog/Handler/FleepHookHandler.php
@@ -45,7 +45,7 @@ class FleepHookHandler extends SocketHandler
      * @param  bool                      $bubble Whether the messages that are handled can bubble up the stack or not
      * @throws MissingExtensionException
      */
-    public function __construct($token, $level = Logger::DEBUG, $bubble = true)
+    public function __construct($token, $level = Logger::DEBUG, bool $bubble = true)
     {
         if (!extension_loaded('openssl')) {
             throw new MissingExtensionException('The OpenSSL PHP extension is required to use the FleepHookHandler');
@@ -74,7 +74,7 @@ class FleepHookHandler extends SocketHandler
      *
      * @param array $record
      */
-    public function write(array $record)
+    public function write(array $record): void
     {
         parent::write($record);
         $this->closeSocket();
diff --git a/src/Monolog/Handler/FlowdockHandler.php b/src/Monolog/Handler/FlowdockHandler.php
index 67d12918..09666622 100644
--- a/src/Monolog/Handler/FlowdockHandler.php
+++ b/src/Monolog/Handler/FlowdockHandler.php
@@ -40,7 +40,7 @@ class FlowdockHandler extends SocketHandler
      *
      * @throws MissingExtensionException if OpenSSL is missing
      */
-    public function __construct($apiToken, $level = Logger::DEBUG, $bubble = true)
+    public function __construct($apiToken, $level = Logger::DEBUG, bool $bubble = true)
     {
         if (!extension_loaded('openssl')) {
             throw new MissingExtensionException('The OpenSSL PHP extension is required to use the FlowdockHandler');
@@ -64,8 +64,6 @@ class FlowdockHandler extends SocketHandler
 
     /**
      * Gets the default formatter.
-     *
-     * @suppress PhanTypeMissingReturn
      */
     protected function getDefaultFormatter(): FormatterInterface
     {
@@ -77,7 +75,7 @@ class FlowdockHandler extends SocketHandler
      *
      * @param array $record
      */
-    protected function write(array $record)
+    protected function write(array $record): void
     {
         parent::write($record);
 
diff --git a/src/Monolog/Handler/FormattableHandlerTrait.php b/src/Monolog/Handler/FormattableHandlerTrait.php
index 2b7e56f9..b1f1b588 100644
--- a/src/Monolog/Handler/FormattableHandlerTrait.php
+++ b/src/Monolog/Handler/FormattableHandlerTrait.php
@@ -28,6 +28,7 @@ trait FormattableHandlerTrait
 
     /**
      * {@inheritdoc}
+     * @suppress PhanTypeMismatchReturn
      */
     public function setFormatter(FormatterInterface $formatter): HandlerInterface
     {
@@ -51,6 +52,8 @@ trait FormattableHandlerTrait
     /**
      * Gets the default formatter.
      *
+     * Overwrite this if the LineFormatter is not a good default for your handler.
+     *
      * @return FormatterInterface
      */
     protected function getDefaultFormatter(): FormatterInterface
diff --git a/src/Monolog/Handler/GelfHandler.php b/src/Monolog/Handler/GelfHandler.php
index 53def822..b5c11355 100644
--- a/src/Monolog/Handler/GelfHandler.php
+++ b/src/Monolog/Handler/GelfHandler.php
@@ -34,7 +34,7 @@ class GelfHandler extends AbstractProcessingHandler
      * @param int                $level     The minimum logging level at which this handler will be triggered
      * @param bool               $bubble    Whether the messages that are handled can bubble up the stack or not
      */
-    public function __construct(PublisherInterface $publisher, $level = Logger::DEBUG, $bubble = true)
+    public function __construct(PublisherInterface $publisher, $level = Logger::DEBUG, bool $bubble = true)
     {
         parent::__construct($level, $bubble);
 
@@ -44,7 +44,7 @@ class GelfHandler extends AbstractProcessingHandler
     /**
      * {@inheritdoc}
      */
-    protected function write(array $record)
+    protected function write(array $record): void
     {
         $this->publisher->publish($record['formatted']);
     }
diff --git a/src/Monolog/Handler/GroupHandler.php b/src/Monolog/Handler/GroupHandler.php
index 30fd68eb..6201ad00 100644
--- a/src/Monolog/Handler/GroupHandler.php
+++ b/src/Monolog/Handler/GroupHandler.php
@@ -28,7 +28,7 @@ class GroupHandler extends Handler implements ProcessableHandlerInterface
      * @param array $handlers Array of Handlers.
      * @param bool  $bubble   Whether the messages that are handled can bubble up the stack or not
      */
-    public function __construct(array $handlers, $bubble = true)
+    public function __construct(array $handlers, bool $bubble = true)
     {
         foreach ($handlers as $handler) {
             if (!$handler instanceof HandlerInterface) {
@@ -73,7 +73,7 @@ class GroupHandler extends Handler implements ProcessableHandlerInterface
     /**
      * {@inheritdoc}
      */
-    public function handleBatch(array $records)
+    public function handleBatch(array $records): void
     {
         if ($this->processors) {
             $processed = [];
diff --git a/src/Monolog/Handler/Handler.php b/src/Monolog/Handler/Handler.php
index 347e7b70..9f43fe10 100644
--- a/src/Monolog/Handler/Handler.php
+++ b/src/Monolog/Handler/Handler.php
@@ -21,7 +21,7 @@ abstract class Handler implements HandlerInterface
     /**
      * {@inheritdoc}
      */
-    public function handleBatch(array $records)
+    public function handleBatch(array $records): void
     {
         foreach ($records as $record) {
             $this->handle($record);
@@ -31,7 +31,7 @@ abstract class Handler implements HandlerInterface
     /**
      * {@inheritdoc}
      */
-    public function close()
+    public function close(): void
     {
     }
 
diff --git a/src/Monolog/Handler/HandlerInterface.php b/src/Monolog/Handler/HandlerInterface.php
index 8ad7e38f..d35161b5 100644
--- a/src/Monolog/Handler/HandlerInterface.php
+++ b/src/Monolog/Handler/HandlerInterface.php
@@ -54,7 +54,7 @@ interface HandlerInterface
      *
      * @param array $records The records to handle (an array of record arrays)
      */
-    public function handleBatch(array $records);
+    public function handleBatch(array $records): void;
 
     /**
      * Closes the handler.
@@ -64,5 +64,5 @@ interface HandlerInterface
      * Implementations have to be idempotent (i.e. it should be possible to call close several times without breakage)
      * and ideally handlers should be able to reopen themselves on handle() after they have been closed.
      */
-    public function close();
+    public function close(): void;
 }
diff --git a/src/Monolog/Handler/HandlerWrapper.php b/src/Monolog/Handler/HandlerWrapper.php
index 28fe57d6..8dc8a846 100644
--- a/src/Monolog/Handler/HandlerWrapper.php
+++ b/src/Monolog/Handler/HandlerWrapper.php
@@ -65,17 +65,17 @@ class HandlerWrapper implements HandlerInterface, ProcessableHandlerInterface, F
     /**
      * {@inheritdoc}
      */
-    public function handleBatch(array $records)
+    public function handleBatch(array $records): void
     {
-        return $this->handler->handleBatch($records);
+        $this->handler->handleBatch($records);
     }
 
     /**
      * {@inheritdoc}
      */
-    public function close()
+    public function close(): void
     {
-        return $this->handler->close();
+        $this->handler->close();
     }
 
     /**
diff --git a/src/Monolog/Handler/HipChatHandler.php b/src/Monolog/Handler/HipChatHandler.php
index 87286e3f..ce09299d 100644
--- a/src/Monolog/Handler/HipChatHandler.php
+++ b/src/Monolog/Handler/HipChatHandler.php
@@ -80,7 +80,7 @@ class HipChatHandler extends SocketHandler
      * @param string $format The format of the messages (default to text, can be set to html if you have html in the messages)
      * @param string $host   The HipChat server hostname.
      */
-    public function __construct($token, $room, $name = 'Monolog', $notify = false, $level = Logger::CRITICAL, $bubble = true, $useSSL = true, $format = 'text', $host = 'api.hipchat.com')
+    public function __construct($token, $room, $name = 'Monolog', $notify = false, $level = Logger::CRITICAL, bool $bubble = true, $useSSL = true, $format = 'text', $host = 'api.hipchat.com')
     {
         $connectionString = $useSSL ? 'ssl://'.$host.':443' : $host.':80';
         parent::__construct($connectionString, $level, $bubble);
@@ -140,11 +140,8 @@ class HipChatHandler extends SocketHandler
 
     /**
      * Builds the header of the API Call
-     *
-     * @param  string $content
-     * @return string
      */
-    private function buildHeader($content)
+    private function buildHeader(string $content): string
     {
         // needed for rooms with special (spaces, etc) characters in the name
         $room = rawurlencode($this->room);
@@ -160,11 +157,8 @@ class HipChatHandler extends SocketHandler
 
     /**
      * Assigns a color to each level of log records.
-     *
-     * @param  int    $level
-     * @return string
      */
-    protected function getAlertColor($level)
+    protected function getAlertColor(int $level): string
     {
         switch (true) {
             case $level >= Logger::ERROR:
@@ -182,10 +176,8 @@ class HipChatHandler extends SocketHandler
 
     /**
      * {@inheritdoc}
-     *
-     * @param array $record
      */
-    protected function write(array $record)
+    protected function write(array $record): void
     {
         parent::write($record);
         $this->finalizeWrite();
@@ -197,7 +189,7 @@ class HipChatHandler extends SocketHandler
      * If we do not read some but close the socket too early, hipchat sometimes
      * drops the request entirely.
      */
-    protected function finalizeWrite()
+    protected function finalizeWrite(): void
     {
         $res = $this->getResource();
         if (is_resource($res)) {
@@ -209,38 +201,25 @@ class HipChatHandler extends SocketHandler
     /**
      * {@inheritdoc}
      */
-    public function handleBatch(array $records)
+    public function handleBatch(array $records): void
     {
         if (count($records) == 0) {
-            return true;
+            return;
         }
 
         $batchRecords = $this->combineRecords($records);
 
-        $handled = false;
         foreach ($batchRecords as $batchRecord) {
-            if ($this->isHandling($batchRecord)) {
-                $this->write($batchRecord);
-                $handled = true;
-            }
+            $this->handle($batchRecord);
         }
-
-        if (!$handled) {
-            return false;
-        }
-
-        return false === $this->bubble;
     }
 
     /**
      * Combines multiple records into one. Error level of the combined record
      * will be the highest level from the given records. Datetime will be taken
      * from the first record.
-     *
-     * @param $records
-     * @return array
      */
-    private function combineRecords($records)
+    private function combineRecords(array $records): array
     {
         $batchRecord = null;
         $batchRecords = [];
diff --git a/src/Monolog/Handler/IFTTTHandler.php b/src/Monolog/Handler/IFTTTHandler.php
index f5d440df..669b3f36 100644
--- a/src/Monolog/Handler/IFTTTHandler.php
+++ b/src/Monolog/Handler/IFTTTHandler.php
@@ -35,7 +35,7 @@ class IFTTTHandler extends AbstractProcessingHandler
      * @param int    $level     The minimum logging level at which this handler will be triggered
      * @param bool   $bubble    Whether the messages that are handled can bubble up the stack or not
      */
-    public function __construct($eventName, $secretKey, $level = Logger::ERROR, $bubble = true)
+    public function __construct($eventName, $secretKey, $level = Logger::ERROR, bool $bubble = true)
     {
         $this->eventName = $eventName;
         $this->secretKey = $secretKey;
@@ -46,7 +46,7 @@ class IFTTTHandler extends AbstractProcessingHandler
     /**
      * {@inheritdoc}
      */
-    public function write(array $record)
+    public function write(array $record): void
     {
         $postData = [
             "value1" => $record["channel"],
diff --git a/src/Monolog/Handler/InsightOpsHandler.php b/src/Monolog/Handler/InsightOpsHandler.php
index bd6dfe60..e211cc75 100644
--- a/src/Monolog/Handler/InsightOpsHandler.php
+++ b/src/Monolog/Handler/InsightOpsHandler.php
@@ -13,7 +13,7 @@ namespace Monolog\Handler;
 
 use Monolog\Logger;
 
- /**
+/**
  * Inspired on LogEntriesHandler.
  *
  * @author Robert Kaufmann III <rok3@rok3.me>
@@ -35,7 +35,7 @@ class InsightOpsHandler extends SocketHandler
      *
      * @throws MissingExtensionException If SSL encryption is set to true and OpenSSL is missing
      */
-    public function __construct($token, $region = 'us', $useSSL = true, $level = Logger::DEBUG, $bubble = true)
+    public function __construct($token, $region = 'us', $useSSL = true, $level = Logger::DEBUG, bool $bubble = true)
     {
         if ($useSSL && !extension_loaded('openssl')) {
             throw new MissingExtensionException('The OpenSSL PHP plugin is required to use SSL encrypted connection for LogEntriesHandler');
diff --git a/src/Monolog/Handler/LogEntriesHandler.php b/src/Monolog/Handler/LogEntriesHandler.php
index c74b9d2e..a2671b0f 100644
--- a/src/Monolog/Handler/LogEntriesHandler.php
+++ b/src/Monolog/Handler/LogEntriesHandler.php
@@ -31,7 +31,7 @@ class LogEntriesHandler extends SocketHandler
      *
      * @throws MissingExtensionException If SSL encryption is set to true and OpenSSL is missing
      */
-    public function __construct($token, $useSSL = true, $level = Logger::DEBUG, $bubble = true)
+    public function __construct($token, $useSSL = true, $level = Logger::DEBUG, bool $bubble = true)
     {
         if ($useSSL && !extension_loaded('openssl')) {
             throw new MissingExtensionException('The OpenSSL PHP plugin is required to use SSL encrypted connection for LogEntriesHandler');
diff --git a/src/Monolog/Handler/LogglyHandler.php b/src/Monolog/Handler/LogglyHandler.php
index 544e7c7f..647c7e13 100644
--- a/src/Monolog/Handler/LogglyHandler.php
+++ b/src/Monolog/Handler/LogglyHandler.php
@@ -32,7 +32,7 @@ class LogglyHandler extends AbstractProcessingHandler
 
     protected $tag = [];
 
-    public function __construct($token, $level = Logger::DEBUG, $bubble = true)
+    public function __construct($token, $level = Logger::DEBUG, bool $bubble = true)
     {
         if (!extension_loaded('curl')) {
             throw new \LogicException('The curl extension is needed to use the LogglyHandler');
@@ -57,12 +57,12 @@ class LogglyHandler extends AbstractProcessingHandler
         }
     }
 
-    protected function write(array $record)
+    protected function write(array $record): void
     {
         $this->send($record["formatted"], self::ENDPOINT_SINGLE);
     }
 
-    public function handleBatch(array $records)
+    public function handleBatch(array $records): void
     {
         $level = $this->level;
 
diff --git a/src/Monolog/Handler/MailHandler.php b/src/Monolog/Handler/MailHandler.php
index 634fbc19..3bbfd565 100644
--- a/src/Monolog/Handler/MailHandler.php
+++ b/src/Monolog/Handler/MailHandler.php
@@ -24,7 +24,7 @@ abstract class MailHandler extends AbstractProcessingHandler
     /**
      * {@inheritdoc}
      */
-    public function handleBatch(array $records)
+    public function handleBatch(array $records): void
     {
         $messages = [];
 
@@ -46,17 +46,17 @@ abstract class MailHandler extends AbstractProcessingHandler
      * @param string $content formatted email body to be sent
      * @param array  $records the array of log records that formed this content
      */
-    abstract protected function send(string $content, array $records);
+    abstract protected function send(string $content, array $records): void;
 
     /**
      * {@inheritdoc}
      */
-    protected function write(array $record)
+    protected function write(array $record): void
     {
         $this->send((string) $record['formatted'], [$record]);
     }
 
-    protected function getHighestRecord(array $records)
+    protected function getHighestRecord(array $records): array
     {
         $highestRecord = null;
         foreach ($records as $record) {
@@ -68,7 +68,7 @@ abstract class MailHandler extends AbstractProcessingHandler
         return $highestRecord;
     }
 
-    protected function isHtmlBody($body)
+    protected function isHtmlBody(string $body): bool
     {
         return substr($body, 0, 1) === '<';
     }
diff --git a/src/Monolog/Handler/MandrillHandler.php b/src/Monolog/Handler/MandrillHandler.php
index 6cf90e7f..f84aa8cc 100644
--- a/src/Monolog/Handler/MandrillHandler.php
+++ b/src/Monolog/Handler/MandrillHandler.php
@@ -12,6 +12,7 @@
 namespace Monolog\Handler;
 
 use Monolog\Logger;
+use Swift;
 
 /**
  * MandrillHandler uses cURL to send the emails to the Mandrill API
@@ -29,7 +30,7 @@ class MandrillHandler extends MailHandler
      * @param int                     $level   The minimum logging level at which this handler will be triggered
      * @param bool                    $bubble  Whether the messages that are handled can bubble up the stack or not
      */
-    public function __construct($apiKey, $message, $level = Logger::ERROR, $bubble = true)
+    public function __construct($apiKey, $message, $level = Logger::ERROR, bool $bubble = true)
     {
         parent::__construct($level, $bubble);
 
@@ -46,16 +47,20 @@ class MandrillHandler extends MailHandler
     /**
      * {@inheritdoc}
      */
-    protected function send(string $content, array $records)
+    protected function send(string $content, array $records): void
     {
-        $mime = null;
+        $mime = 'text/plain';
         if ($this->isHtmlBody($content)) {
             $mime = 'text/html';
         }
 
         $message = clone $this->message;
         $message->setBody($content, $mime);
-        $message->setDate(time());
+        if (version_compare(Swift::VERSION, '6.0.0', '>=')) {
+            $message->setDate(new \DateTimeImmutable());
+        } else {
+            $message->setDate(time());
+        }
 
         $ch = curl_init();
 
diff --git a/src/Monolog/Handler/MongoDBHandler.php b/src/Monolog/Handler/MongoDBHandler.php
index 5415ee52..98a23822 100644
--- a/src/Monolog/Handler/MongoDBHandler.php
+++ b/src/Monolog/Handler/MongoDBHandler.php
@@ -46,7 +46,7 @@ class MongoDBHandler extends AbstractProcessingHandler
      * @param int            $level      The minimum logging level at which this handler will be triggered
      * @param bool           $bubble     Whether the messages that are handled can bubble up the stack or not
      */
-    public function __construct($mongodb, $database, $collection, $level = Logger::DEBUG, $bubble = true)
+    public function __construct($mongodb, $database, $collection, $level = Logger::DEBUG, bool $bubble = true)
     {
         if (!($mongodb instanceof Client || $mongodb instanceof Manager)) {
             throw new \InvalidArgumentException('MongoDB\Client or MongoDB\Driver\Manager instance required');
@@ -62,7 +62,7 @@ class MongoDBHandler extends AbstractProcessingHandler
         parent::__construct($level, $bubble);
     }
 
-    protected function write(array $record)
+    protected function write(array $record): void
     {
         if (isset($this->collection)) {
             $this->collection->insertOne($record['formatted']);
diff --git a/src/Monolog/Handler/NativeMailerHandler.php b/src/Monolog/Handler/NativeMailerHandler.php
index b597761e..b6f8dbbb 100644
--- a/src/Monolog/Handler/NativeMailerHandler.php
+++ b/src/Monolog/Handler/NativeMailerHandler.php
@@ -72,7 +72,7 @@ class NativeMailerHandler extends MailHandler
      * @param bool         $bubble         Whether the messages that are handled can bubble up the stack or not
      * @param int          $maxColumnWidth The maximum column width that the message lines will have
      */
-    public function __construct($to, $subject, $from, $level = Logger::ERROR, $bubble = true, $maxColumnWidth = 70)
+    public function __construct($to, $subject, $from, $level = Logger::ERROR, bool $bubble = true, $maxColumnWidth = 70)
     {
         parent::__construct($level, $bubble);
         $this->to = (array) $to;
@@ -115,7 +115,7 @@ class NativeMailerHandler extends MailHandler
     /**
      * {@inheritdoc}
      */
-    protected function send(string $content, array $records)
+    protected function send(string $content, array $records): void
     {
         $contentType = $this->getContentType() ?: ($this->isHtmlBody($content) ? 'text/html' : 'text/plain');
 
diff --git a/src/Monolog/Handler/NewRelicHandler.php b/src/Monolog/Handler/NewRelicHandler.php
index d757067b..c4540b69 100644
--- a/src/Monolog/Handler/NewRelicHandler.php
+++ b/src/Monolog/Handler/NewRelicHandler.php
@@ -72,7 +72,7 @@ class NewRelicHandler extends AbstractProcessingHandler
     /**
      * {@inheritDoc}
      */
-    protected function write(array $record)
+    protected function write(array $record): void
     {
         if (!$this->isNewRelicEnabled()) {
             throw new MissingExtensionException('The newrelic PHP extension is required to use the NewRelicHandler');
diff --git a/src/Monolog/Handler/PHPConsoleHandler.php b/src/Monolog/Handler/PHPConsoleHandler.php
index c2b7b3e8..f40e3d5f 100644
--- a/src/Monolog/Handler/PHPConsoleHandler.php
+++ b/src/Monolog/Handler/PHPConsoleHandler.php
@@ -59,7 +59,7 @@ class PHPConsoleHandler extends AbstractProcessingHandler
         'dumperItemSizeLimit' => 5000, // int Maximum length of any string or dumped array item
         'dumperDumpSizeLimit' => 500000, // int Maximum approximate size of dumped vars result formatted in JSON
         'detectDumpTraceAndSource' => false, // bool Autodetect and append trace data to debug
-        'dataStorage' => null, // PhpConsole\Storage|null Fixes problem with custom $_SESSION handler(see http://goo.gl/Ne8juJ)
+        'dataStorage' => null, // \PhpConsole\Storage|null Fixes problem with custom $_SESSION handler(see http://goo.gl/Ne8juJ)
     ];
 
     /** @var Connector */
@@ -68,11 +68,11 @@ class PHPConsoleHandler extends AbstractProcessingHandler
     /**
      * @param  array             $options   See \Monolog\Handler\PHPConsoleHandler::$options for more details
      * @param  Connector|null    $connector Instance of \PhpConsole\Connector class (optional)
-     * @param  int               $level
+     * @param  int|string        $level
      * @param  bool              $bubble
      * @throws \RuntimeException
      */
-    public function __construct(array $options = [], Connector $connector = null, $level = Logger::DEBUG, $bubble = true)
+    public function __construct(array $options = [], ?Connector $connector = null, $level = Logger::DEBUG, bool $bubble = true)
     {
         if (!class_exists('PhpConsole\Connector')) {
             throw new \RuntimeException('PHP Console library not found. See https://github.com/barbushin/php-console#installation');
@@ -92,7 +92,10 @@ class PHPConsoleHandler extends AbstractProcessingHandler
         return array_replace($this->options, $options);
     }
 
-    private function initConnector(Connector $connector = null)
+    /**
+     * @suppress PhanTypeMismatchArgument
+     */
+    private function initConnector(Connector $connector = null): Connector
     {
         if (!$connector) {
             if ($this->options['dataStorage']) {
@@ -147,12 +150,12 @@ class PHPConsoleHandler extends AbstractProcessingHandler
         return $connector;
     }
 
-    public function getConnector()
+    public function getConnector(): Connector
     {
         return $this->connector;
     }
 
-    public function getOptions()
+    public function getOptions(): array
     {
         return $this->options;
     }
@@ -172,7 +175,7 @@ class PHPConsoleHandler extends AbstractProcessingHandler
      * @param  array $record
      * @return void
      */
-    protected function write(array $record)
+    protected function write(array $record): void
     {
         if ($record['level'] < Logger::NOTICE) {
             $this->handleDebugRecord($record);
@@ -183,7 +186,7 @@ class PHPConsoleHandler extends AbstractProcessingHandler
         }
     }
 
-    private function handleDebugRecord(array $record)
+    private function handleDebugRecord(array $record): void
     {
         $tags = $this->getRecordTags($record);
         $message = $record['message'];
@@ -193,12 +196,12 @@ class PHPConsoleHandler extends AbstractProcessingHandler
         $this->connector->getDebugDispatcher()->dispatchDebug($message, $tags, $this->options['classesPartialsTraceIgnore']);
     }
 
-    private function handleExceptionRecord(array $record)
+    private function handleExceptionRecord(array $record): void
     {
         $this->connector->getErrorsDispatcher()->dispatchException($record['context']['exception']);
     }
 
-    private function handleErrorRecord(array $record)
+    private function handleErrorRecord(array $record): void
     {
         $context = $record['context'];
 
diff --git a/src/Monolog/Handler/ProcessHandler.php b/src/Monolog/Handler/ProcessHandler.php
index 8cf6087b..4478fe1d 100644
--- a/src/Monolog/Handler/ProcessHandler.php
+++ b/src/Monolog/Handler/ProcessHandler.php
@@ -39,7 +39,7 @@ class ProcessHandler extends AbstractProcessingHandler
     private $command;
 
     /**
-     * @var string
+     * @var ?string
      */
     private $cwd;
 
@@ -62,10 +62,10 @@ class ProcessHandler extends AbstractProcessingHandler
      *                                            especially if you do not use the $cwd parameter.
      * @param  string|int                $level   The minimum logging level at which this handler will be triggered.
      * @param  bool                      $bubble  Whether the messages that are handled can bubble up the stack or not.
-     * @param  string                    $cwd     "Current working directory" (CWD) for the process to be executed in.
+     * @param  ?string                   $cwd     "Current working directory" (CWD) for the process to be executed in.
      * @throws \InvalidArgumentException
      */
-    public function __construct(string $command, $level = Logger::DEBUG, bool $bubble = true, string $cwd = null)
+    public function __construct(string $command, $level = Logger::DEBUG, bool $bubble = true, ?string $cwd = null)
     {
         if ($command === '') {
             throw new \InvalidArgumentException('The command argument must be a non-empty string.');
@@ -83,11 +83,9 @@ class ProcessHandler extends AbstractProcessingHandler
     /**
      * Writes the record down to the log of the implementing handler
      *
-     * @param  array                     $record
      * @throws \UnexpectedValueException
-     * @return void
      */
-    protected function write(array $record)
+    protected function write(array $record): void
     {
         $this->ensureProcessIsStarted();
 
@@ -102,10 +100,8 @@ class ProcessHandler extends AbstractProcessingHandler
     /**
      * Makes sure that the process is actually started, and if not, starts it,
      * assigns the stream pipes, and handles startup errors, if any.
-     *
-     * @return void
      */
-    private function ensureProcessIsStarted()
+    private function ensureProcessIsStarted(): void
     {
         if (is_resource($this->process) === false) {
             $this->startProcess();
@@ -116,10 +112,8 @@ class ProcessHandler extends AbstractProcessingHandler
 
     /**
      * Starts the actual process and sets all streams to non-blocking.
-     *
-     * @return void
      */
-    private function startProcess()
+    private function startProcess(): void
     {
         $this->process = proc_open($this->command, self::DESCRIPTOR_SPEC, $this->pipes, $this->cwd);
 
@@ -132,9 +126,8 @@ class ProcessHandler extends AbstractProcessingHandler
      * Selects the STDERR stream, handles upcoming startup errors, and throws an exception, if any.
      *
      * @throws \UnexpectedValueException
-     * @return void
      */
-    private function handleStartupErrors()
+    private function handleStartupErrors(): void
     {
         $selected = $this->selectErrorStream();
         if (false === $selected) {
@@ -169,7 +162,7 @@ class ProcessHandler extends AbstractProcessingHandler
      * @codeCoverageIgnore
      * @return string Empty string if there are no errors.
      */
-    protected function readProcessErrors()
+    protected function readProcessErrors(): string
     {
         return stream_get_contents($this->pipes[2]);
     }
@@ -178,18 +171,16 @@ class ProcessHandler extends AbstractProcessingHandler
      * Writes to the input stream of the opened process.
      *
      * @codeCoverageIgnore
-     * @param $string
-     * @return void
      */
-    protected function writeProcessInput($string)
+    protected function writeProcessInput(string $string): void
     {
-        fwrite($this->pipes[0], (string) $string);
+        fwrite($this->pipes[0], $string);
     }
 
     /**
      * {@inheritdoc}
      */
-    public function close()
+    public function close(): void
     {
         if (is_resource($this->process)) {
             foreach ($this->pipes as $pipe) {
diff --git a/src/Monolog/Handler/ProcessableHandlerTrait.php b/src/Monolog/Handler/ProcessableHandlerTrait.php
index bba940e8..58821100 100644
--- a/src/Monolog/Handler/ProcessableHandlerTrait.php
+++ b/src/Monolog/Handler/ProcessableHandlerTrait.php
@@ -25,6 +25,7 @@ trait ProcessableHandlerTrait
 
     /**
      * {@inheritdoc}
+     * @suppress PhanTypeMismatchReturn
      */
     public function pushProcessor(callable $callback): HandlerInterface
     {
@@ -47,11 +48,8 @@ trait ProcessableHandlerTrait
 
     /**
      * Processes a record.
-     *
-     * @param  array $record
-     * @return array
      */
-    protected function processRecord(array $record)
+    protected function processRecord(array $record): array
     {
         foreach ($this->processors as $processor) {
             $record = $processor($record);
diff --git a/src/Monolog/Handler/PsrHandler.php b/src/Monolog/Handler/PsrHandler.php
index e39233b4..b59e99af 100644
--- a/src/Monolog/Handler/PsrHandler.php
+++ b/src/Monolog/Handler/PsrHandler.php
@@ -33,7 +33,7 @@ class PsrHandler extends AbstractHandler
      * @param int             $level  The minimum logging level at which this handler will be triggered
      * @param bool            $bubble Whether the messages that are handled can bubble up the stack or not
      */
-    public function __construct(LoggerInterface $logger, $level = Logger::DEBUG, $bubble = true)
+    public function __construct(LoggerInterface $logger, $level = Logger::DEBUG, bool $bubble = true)
     {
         parent::__construct($level, $bubble);
 
diff --git a/src/Monolog/Handler/PushoverHandler.php b/src/Monolog/Handler/PushoverHandler.php
index 3e683422..c6cba6e8 100644
--- a/src/Monolog/Handler/PushoverHandler.php
+++ b/src/Monolog/Handler/PushoverHandler.php
@@ -79,7 +79,7 @@ class PushoverHandler extends SocketHandler
      * @param int          $retry             The retry parameter specifies how often (in seconds) the Pushover servers will send the same notification to the user.
      * @param int          $expire            The expire parameter specifies how many seconds your notification will continue to be retried for (every retry seconds).
      */
-    public function __construct($token, $users, $title = null, $level = Logger::CRITICAL, $bubble = true, $useSSL = true, $highPriorityLevel = Logger::CRITICAL, $emergencyLevel = Logger::EMERGENCY, $retry = 30, $expire = 25200)
+    public function __construct($token, $users, $title = null, $level = Logger::CRITICAL, bool $bubble = true, $useSSL = true, $highPriorityLevel = Logger::CRITICAL, $emergencyLevel = Logger::EMERGENCY, $retry = 30, $expire = 25200)
     {
         $connectionString = $useSSL ? 'ssl://api.pushover.net:443' : 'api.pushover.net:80';
         parent::__construct($connectionString, $level, $bubble);
@@ -152,7 +152,7 @@ class PushoverHandler extends SocketHandler
         return $header;
     }
 
-    protected function write(array $record)
+    protected function write(array $record): void
     {
         foreach ($this->users as $user) {
             $this->user = $user;
diff --git a/src/Monolog/Handler/RavenHandler.php b/src/Monolog/Handler/RavenHandler.php
index 7ea5fd7d..801e52c1 100644
--- a/src/Monolog/Handler/RavenHandler.php
+++ b/src/Monolog/Handler/RavenHandler.php
@@ -59,7 +59,7 @@ class RavenHandler extends AbstractProcessingHandler
      * @param int          $level       The minimum logging level at which this handler will be triggered
      * @param bool         $bubble      Whether the messages that are handled can bubble up the stack or not
      */
-    public function __construct(Raven_Client $ravenClient, $level = Logger::DEBUG, $bubble = true)
+    public function __construct(Raven_Client $ravenClient, $level = Logger::DEBUG, bool $bubble = true)
     {
         parent::__construct($level, $bubble);
 
@@ -69,7 +69,7 @@ class RavenHandler extends AbstractProcessingHandler
     /**
      * {@inheritdoc}
      */
-    public function handleBatch(array $records)
+    public function handleBatch(array $records): void
     {
         $level = $this->level;
 
@@ -130,8 +130,9 @@ class RavenHandler extends AbstractProcessingHandler
 
     /**
      * {@inheritdoc}
+     * @suppress PhanTypeMismatchArgument
      */
-    protected function write(array $record)
+    protected function write(array $record): void
     {
         /** @var bool|null|array This is false, unless set below to null or an array of data, when we read the current user context */
         $previousUserContext = false;
diff --git a/src/Monolog/Handler/RedisHandler.php b/src/Monolog/Handler/RedisHandler.php
index e7ddb44b..ede8be31 100644
--- a/src/Monolog/Handler/RedisHandler.php
+++ b/src/Monolog/Handler/RedisHandler.php
@@ -55,7 +55,7 @@ class RedisHandler extends AbstractProcessingHandler
     /**
      * {@inheritDoc}
      */
-    protected function write(array $record)
+    protected function write(array $record): void
     {
         if ($this->capSize) {
             $this->writeCapped($record);
diff --git a/src/Monolog/Handler/RollbarHandler.php b/src/Monolog/Handler/RollbarHandler.php
index 2f35093c..4df6f15e 100644
--- a/src/Monolog/Handler/RollbarHandler.php
+++ b/src/Monolog/Handler/RollbarHandler.php
@@ -63,7 +63,7 @@ class RollbarHandler extends AbstractProcessingHandler
      * @param int           $level         The minimum logging level at which this handler will be triggered
      * @param bool          $bubble        Whether the messages that are handled can bubble up the stack or not
      */
-    public function __construct(RollbarLogger $rollbarLogger, $level = Logger::ERROR, $bubble = true)
+    public function __construct(RollbarLogger $rollbarLogger, $level = Logger::ERROR, bool $bubble = true)
     {
         $this->rollbarLogger = $rollbarLogger;
 
@@ -73,7 +73,7 @@ class RollbarHandler extends AbstractProcessingHandler
     /**
      * {@inheritdoc}
      */
-    protected function write(array $record)
+    protected function write(array $record): void
     {
         if (!$this->initialized) {
             // __destructor() doesn't get called on Fatal errors
@@ -113,7 +113,7 @@ class RollbarHandler extends AbstractProcessingHandler
     /**
      * {@inheritdoc}
      */
-    public function close()
+    public function close(): void
     {
         $this->flush();
     }
diff --git a/src/Monolog/Handler/RotatingFileHandler.php b/src/Monolog/Handler/RotatingFileHandler.php
index d9733ba0..32fbb877 100644
--- a/src/Monolog/Handler/RotatingFileHandler.php
+++ b/src/Monolog/Handler/RotatingFileHandler.php
@@ -44,7 +44,7 @@ class RotatingFileHandler extends StreamHandler
      * @param int|null $filePermission Optional file permissions (default (0644) are only for owner read/write)
      * @param bool     $useLocking     Try to lock log file before doing any writes
      */
-    public function __construct($filename, $maxFiles = 0, $level = Logger::DEBUG, $bubble = true, $filePermission = null, $useLocking = false)
+    public function __construct($filename, $maxFiles = 0, $level = Logger::DEBUG, bool $bubble = true, $filePermission = null, $useLocking = false)
     {
         $this->filename = $filename;
         $this->maxFiles = (int) $maxFiles;
@@ -58,7 +58,7 @@ class RotatingFileHandler extends StreamHandler
     /**
      * {@inheritdoc}
      */
-    public function close()
+    public function close(): void
     {
         parent::close();
 
@@ -91,7 +91,7 @@ class RotatingFileHandler extends StreamHandler
     /**
      * {@inheritdoc}
      */
-    protected function write(array $record)
+    protected function write(array $record): void
     {
         // on the first record written, if the log is new, we should rotate (once per day)
         if (null === $this->mustRotate) {
@@ -109,7 +109,7 @@ class RotatingFileHandler extends StreamHandler
     /**
      * Rotates the files.
      */
-    protected function rotate()
+    protected function rotate(): void
     {
         // update filename
         $this->url = $this->getTimedFilename();
@@ -135,7 +135,8 @@ class RotatingFileHandler extends StreamHandler
             if (is_writable($file)) {
                 // suppress errors here as unlink() might fail if two processes
                 // are cleaning up/rotating at the same time
-                set_error_handler(function ($errno, $errstr, $errfile, $errline) {
+                set_error_handler(function (int $errno, string $errstr, string $errfile, int $errline): bool {
+                    return false;
                 });
                 unlink($file);
                 restore_error_handler();
diff --git a/src/Monolog/Handler/SendGridHandler.php b/src/Monolog/Handler/SendGridHandler.php
index 7d82d946..c154a5d1 100644
--- a/src/Monolog/Handler/SendGridHandler.php
+++ b/src/Monolog/Handler/SendGridHandler.php
@@ -72,7 +72,7 @@ class SendGridHandler extends MailHandler
     /**
      * {@inheritdoc}
      */
-    protected function send(string $content, array $records)
+    protected function send(string $content, array $records): void
     {
         $message = [];
         $message['api_user'] = $this->apiUser;
diff --git a/src/Monolog/Handler/Slack/SlackRecord.php b/src/Monolog/Handler/Slack/SlackRecord.php
index 91413e5f..36f43734 100755
--- a/src/Monolog/Handler/Slack/SlackRecord.php
+++ b/src/Monolog/Handler/Slack/SlackRecord.php
@@ -35,13 +35,13 @@ class SlackRecord
 
     /**
      * Slack channel (encoded ID or name)
-     * @var string|null
+     * @var ?string
      */
     private $channel;
 
     /**
      * Name of a bot
-     * @var string|null
+     * @var ?string
      */
     private $username;
 
@@ -177,9 +177,6 @@ class SlackRecord
     /**
      * Returned a Slack message attachment color associated with
      * provided level.
-     *
-     * @param  int    $level
-     * @return string
      */
     public function getAttachmentColor(int $level): string
     {
@@ -197,10 +194,6 @@ class SlackRecord
 
     /**
      * Stringifies an array of key/value pairs to be used in attachment fields
-     *
-     * @param array $fields
-     *
-     * @return string
      */
     public function stringify(array $fields): string
     {
@@ -215,23 +208,17 @@ class SlackRecord
             : json_encode($normalized, JSON_UNESCAPED_UNICODE);
     }
 
-    /**
-     * Sets the formatter
-     *
-     * @param FormatterInterface $formatter
-     */
-    public function setFormatter(FormatterInterface $formatter): void
+    public function setFormatter(FormatterInterface $formatter): self
     {
         $this->formatter = $formatter;
+
+        return $this;
     }
 
     /**
      * Generates attachment field
      *
-     * @param string       $title
      * @param string|array $value
-     *
-     * @return array
      */
     private function generateAttachmentField(string $title, $value): array
     {
@@ -248,10 +235,6 @@ class SlackRecord
 
     /**
      * Generates a collection of attachment fields from array
-     *
-     * @param array $data
-     *
-     * @return array
      */
     private function generateAttachmentFields(array $data): array
     {
@@ -265,10 +248,6 @@ class SlackRecord
 
     /**
      * Get a copy of record with fields excluded according to $this->excludeFields
-     *
-     * @param array $record
-     *
-     * @return array
      */
     private function excludeFields(array $record): array
     {
diff --git a/src/Monolog/Handler/SlackHandler.php b/src/Monolog/Handler/SlackHandler.php
index 6f671ac1..30a10fc1 100644
--- a/src/Monolog/Handler/SlackHandler.php
+++ b/src/Monolog/Handler/SlackHandler.php
@@ -48,7 +48,7 @@ class SlackHandler extends SocketHandler
      * @param  array                     $excludeFields          Dot separated list of fields to exclude from slack message. E.g. ['context.field1', 'extra.field2']
      * @throws MissingExtensionException If no OpenSSL PHP extension configured
      */
-    public function __construct($token, $channel, $username = null, $useAttachment = true, $iconEmoji = null, $level = Logger::CRITICAL, $bubble = true, $useShortAttachment = false, $includeContextAndExtra = false, array $excludeFields = array())
+    public function __construct($token, $channel, $username = null, $useAttachment = true, $iconEmoji = null, $level = Logger::CRITICAL, bool $bubble = true, $useShortAttachment = false, $includeContextAndExtra = false, array $excludeFields = array())
     {
         if (!extension_loaded('openssl')) {
             throw new MissingExtensionException('The OpenSSL PHP extension is required to use the SlackHandler');
@@ -145,7 +145,7 @@ class SlackHandler extends SocketHandler
      *
      * @param array $record
      */
-    protected function write(array $record)
+    protected function write(array $record): void
     {
         parent::write($record);
         $this->finalizeWrite();
diff --git a/src/Monolog/Handler/SlackWebhookHandler.php b/src/Monolog/Handler/SlackWebhookHandler.php
index 2904db3f..9c26486c 100644
--- a/src/Monolog/Handler/SlackWebhookHandler.php
+++ b/src/Monolog/Handler/SlackWebhookHandler.php
@@ -47,7 +47,7 @@ class SlackWebhookHandler extends AbstractProcessingHandler
      * @param bool        $bubble                 Whether the messages that are handled can bubble up the stack or not
      * @param array       $excludeFields          Dot separated list of fields to exclude from slack message. E.g. ['context.field1', 'extra.field2']
      */
-    public function __construct($webhookUrl, $channel = null, $username = null, $useAttachment = true, $iconEmoji = null, $useShortAttachment = false, $includeContextAndExtra = false, $level = Logger::CRITICAL, $bubble = true, array $excludeFields = array())
+    public function __construct($webhookUrl, $channel = null, $username = null, $useAttachment = true, $iconEmoji = null, $useShortAttachment = false, $includeContextAndExtra = false, $level = Logger::CRITICAL, bool $bubble = true, array $excludeFields = array())
     {
         parent::__construct($level, $bubble);
 
@@ -79,7 +79,7 @@ class SlackWebhookHandler extends AbstractProcessingHandler
      *
      * @param array $record
      */
-    protected function write(array $record)
+    protected function write(array $record): void
     {
         $postData = $this->slackRecord->getSlackData($record);
         $postString = json_encode($postData);
diff --git a/src/Monolog/Handler/SlackbotHandler.php b/src/Monolog/Handler/SlackbotHandler.php
index dd2db593..3a1dfa5c 100644
--- a/src/Monolog/Handler/SlackbotHandler.php
+++ b/src/Monolog/Handler/SlackbotHandler.php
@@ -46,7 +46,7 @@ class SlackbotHandler extends AbstractProcessingHandler
      * @param int    $level     The minimum logging level at which this handler will be triggered
      * @param bool   $bubble    Whether the messages that are handled can bubble up the stack or not
      */
-    public function __construct($slackTeam, $token, $channel, $level = Logger::CRITICAL, $bubble = true)
+    public function __construct($slackTeam, $token, $channel, $level = Logger::CRITICAL, bool $bubble = true)
     {
         parent::__construct($level, $bubble);
 
@@ -60,7 +60,7 @@ class SlackbotHandler extends AbstractProcessingHandler
      *
      * @param array $record
      */
-    protected function write(array $record)
+    protected function write(array $record): void
     {
         $slackbotUrl = sprintf(
             'https://%s.slack.com/services/hooks/slackbot?token=%s&channel=%s',
diff --git a/src/Monolog/Handler/SocketHandler.php b/src/Monolog/Handler/SocketHandler.php
index 36ea0b5f..3dc6d975 100644
--- a/src/Monolog/Handler/SocketHandler.php
+++ b/src/Monolog/Handler/SocketHandler.php
@@ -30,6 +30,7 @@ class SocketHandler extends AbstractProcessingHandler
     /** @var float */
     private $writingTimeout = 10;
     private $lastSentBytes = null;
+    /** @var int */
     private $chunkSize = null;
     private $persistent = false;
     private $errno;
@@ -41,7 +42,7 @@ class SocketHandler extends AbstractProcessingHandler
      * @param int    $level            The minimum logging level at which this handler will be triggered
      * @param bool   $bubble           Whether the messages that are handled can bubble up the stack or not
      */
-    public function __construct($connectionString, $level = Logger::DEBUG, $bubble = true)
+    public function __construct($connectionString, $level = Logger::DEBUG, bool $bubble = true)
     {
         parent::__construct($level, $bubble);
         $this->connectionString = $connectionString;
@@ -56,7 +57,7 @@ class SocketHandler extends AbstractProcessingHandler
      * @throws \UnexpectedValueException
      * @throws \RuntimeException
      */
-    protected function write(array $record)
+    protected function write(array $record): void
     {
         $this->connectIfNotConnected();
         $data = $this->generateDataStream($record);
@@ -66,7 +67,7 @@ class SocketHandler extends AbstractProcessingHandler
     /**
      * We will not close a PersistentSocket instance so it can be reused in other requests.
      */
-    public function close()
+    public function close(): void
     {
         if (!$this->isPersistent()) {
             $this->closeSocket();
@@ -76,7 +77,7 @@ class SocketHandler extends AbstractProcessingHandler
     /**
      * Close socket, if open
      */
-    public function closeSocket()
+    public function closeSocket(): void
     {
         if (is_resource($this->resource)) {
             fclose($this->resource);
@@ -85,23 +86,19 @@ class SocketHandler extends AbstractProcessingHandler
     }
 
     /**
-     * Set socket connection to nbe persistent. It only has effect before the connection is initiated.
-     *
-     * @param bool $persistent
+     * Set socket connection to be persistent. It only has effect before the connection is initiated.
      */
-    public function setPersistent($persistent)
+    public function setPersistent(bool $persistent): void
     {
-        $this->persistent = (bool) $persistent;
+        $this->persistent = $persistent;
     }
 
     /**
      * Set connection timeout.  Only has effect before we connect.
      *
-     * @param float $seconds
-     *
      * @see http://php.net/manual/en/function.fsockopen.php
      */
-    public function setConnectionTimeout($seconds)
+    public function setConnectionTimeout(float $seconds): void
     {
         $this->validateTimeout($seconds);
         $this->connectionTimeout = (float) $seconds;
@@ -110,11 +107,9 @@ class SocketHandler extends AbstractProcessingHandler
     /**
      * Set write timeout. Only has effect before we connect.
      *
-     * @param float $seconds
-     *
      * @see http://php.net/manual/en/function.stream-set-timeout.php
      */
-    public function setTimeout($seconds)
+    public function setTimeout(float $seconds): void
     {
         $this->validateTimeout($seconds);
         $this->timeout = (float) $seconds;
@@ -125,7 +120,7 @@ class SocketHandler extends AbstractProcessingHandler
      *
      * @param float $seconds 0 for no timeout
      */
-    public function setWritingTimeout($seconds)
+    public function setWritingTimeout(float $seconds): void
     {
         $this->validateTimeout($seconds);
         $this->writingTimeout = (float) $seconds;
@@ -133,20 +128,16 @@ class SocketHandler extends AbstractProcessingHandler
 
     /**
      * Set chunk size. Only has effect during connection in the writing cycle.
-     *
-     * @param float $bytes
      */
-    public function setChunkSize($bytes)
+    public function setChunkSize(int $bytes): void
     {
         $this->chunkSize = $bytes;
     }
 
     /**
      * Get current connection string
-     *
-     * @return string
      */
-    public function getConnectionString()
+    public function getConnectionString(): string
     {
         return $this->connectionString;
     }
@@ -189,10 +180,8 @@ class SocketHandler extends AbstractProcessingHandler
 
     /**
      * Get current chunk size
-     *
-     * @return float
      */
-    public function getChunkSize()
+    public function getChunkSize(): int
     {
         return $this->chunkSize;
     }
@@ -201,10 +190,8 @@ class SocketHandler extends AbstractProcessingHandler
      * Check to see if the socket is currently available.
      *
      * UDP might appear to be connected but might fail when writing.  See http://php.net/fsockopen for details.
-     *
-     * @return bool
      */
-    public function isConnected()
+    public function isConnected(): bool
     {
         return is_resource($this->resource)
             && !feof($this->resource);  // on TCP - other party can close connection.
diff --git a/src/Monolog/Handler/SqsHandler.php b/src/Monolog/Handler/SqsHandler.php
index ed595c71..f282d023 100644
--- a/src/Monolog/Handler/SqsHandler.php
+++ b/src/Monolog/Handler/SqsHandler.php
@@ -31,7 +31,7 @@ class SqsHandler extends AbstractProcessingHandler
     /** @var string */
     private $queueUrl;
 
-    public function __construct(SqsClient $sqsClient, $queueUrl, $level = Logger::DEBUG, $bubble = true)
+    public function __construct(SqsClient $sqsClient, $queueUrl, $level = Logger::DEBUG, bool $bubble = true)
     {
         parent::__construct($level, $bubble);
 
@@ -44,7 +44,7 @@ class SqsHandler extends AbstractProcessingHandler
      *
      * @param array $record
      */
-    protected function write(array $record)
+    protected function write(array $record): void
     {
         if (!isset($record['formatted']) || 'string' !== gettype($record['formatted'])) {
             throw new \InvalidArgumentException('SqsHandler accepts only formatted records as a string');
diff --git a/src/Monolog/Handler/StreamHandler.php b/src/Monolog/Handler/StreamHandler.php
index 6631ef4e..92ccc04d 100644
--- a/src/Monolog/Handler/StreamHandler.php
+++ b/src/Monolog/Handler/StreamHandler.php
@@ -41,7 +41,7 @@ class StreamHandler extends AbstractProcessingHandler
      * @throws \Exception                If a missing directory is not buildable
      * @throws \InvalidArgumentException If stream is not a resource or string
      */
-    public function __construct($stream, $level = Logger::DEBUG, $bubble = true, $filePermission = null, $useLocking = false)
+    public function __construct($stream, $level = Logger::DEBUG, bool $bubble = true, $filePermission = null, $useLocking = false)
     {
         parent::__construct($level, $bubble);
         if (is_resource($stream)) {
@@ -59,7 +59,7 @@ class StreamHandler extends AbstractProcessingHandler
     /**
      * {@inheritdoc}
      */
-    public function close()
+    public function close(): void
     {
         if ($this->url && is_resource($this->stream)) {
             fclose($this->stream);
@@ -90,7 +90,7 @@ class StreamHandler extends AbstractProcessingHandler
     /**
      * {@inheritdoc}
      */
-    protected function write(array $record)
+    protected function write(array $record): void
     {
         if (!is_resource($this->stream)) {
             if (null === $this->url || '' === $this->url) {
@@ -138,12 +138,7 @@ class StreamHandler extends AbstractProcessingHandler
         $this->errorMessage = preg_replace('{^(fopen|mkdir)\(.*?\): }', '', $msg);
     }
 
-    /**
-     * @param string $stream
-     *
-     * @return null|string
-     */
-    private function getDirFromStream($stream)
+    private function getDirFromStream(string $stream): ?string
     {
         $pos = strpos($stream, '://');
         if ($pos === false) {
@@ -154,7 +149,7 @@ class StreamHandler extends AbstractProcessingHandler
             return dirname(substr($stream, 7));
         }
 
-        return;
+        return null;
     }
 
     private function createDir()
diff --git a/src/Monolog/Handler/SwiftMailerHandler.php b/src/Monolog/Handler/SwiftMailerHandler.php
index 73ef3cfc..4fa14ca8 100644
--- a/src/Monolog/Handler/SwiftMailerHandler.php
+++ b/src/Monolog/Handler/SwiftMailerHandler.php
@@ -44,7 +44,7 @@ class SwiftMailerHandler extends MailHandler
     /**
      * {@inheritdoc}
      */
-    protected function send(string $content, array $records)
+    protected function send(string $content, array $records): void
     {
         $this->mailer->send($this->buildMessage($content, $records));
     }
@@ -85,7 +85,7 @@ class SwiftMailerHandler extends MailHandler
             $message->setSubject($subjectFormatter->format($this->getHighestRecord($records)));
         }
 
-        $mime = null;
+        $mime = 'text/plain';
         if ($this->isHtmlBody($content)) {
             $mime = 'text/html';
         }
diff --git a/src/Monolog/Handler/SyslogHandler.php b/src/Monolog/Handler/SyslogHandler.php
index df7c89a8..fb7faef6 100644
--- a/src/Monolog/Handler/SyslogHandler.php
+++ b/src/Monolog/Handler/SyslogHandler.php
@@ -38,7 +38,7 @@ class SyslogHandler extends AbstractSyslogHandler
      * @param bool   $bubble   Whether the messages that are handled can bubble up the stack or not
      * @param int    $logopts  Option flags for the openlog() call, defaults to LOG_PID
      */
-    public function __construct($ident, $facility = LOG_USER, $level = Logger::DEBUG, $bubble = true, $logopts = LOG_PID)
+    public function __construct($ident, $facility = LOG_USER, $level = Logger::DEBUG, bool $bubble = true, $logopts = LOG_PID)
     {
         parent::__construct($facility, $level, $bubble);
 
@@ -49,7 +49,7 @@ class SyslogHandler extends AbstractSyslogHandler
     /**
      * {@inheritdoc}
      */
-    public function close()
+    public function close(): void
     {
         closelog();
     }
@@ -57,7 +57,7 @@ class SyslogHandler extends AbstractSyslogHandler
     /**
      * {@inheritdoc}
      */
-    protected function write(array $record)
+    protected function write(array $record): void
     {
         if (!openlog($this->ident, $this->logopts, $this->facility)) {
             throw new \LogicException('Can\'t open syslog for ident "'.$this->ident.'" and facility "'.$this->facility.'"');
diff --git a/src/Monolog/Handler/SyslogUdp/UdpSocket.php b/src/Monolog/Handler/SyslogUdp/UdpSocket.php
index f1801b37..17e2aef0 100644
--- a/src/Monolog/Handler/SyslogUdp/UdpSocket.php
+++ b/src/Monolog/Handler/SyslogUdp/UdpSocket.php
@@ -15,13 +15,14 @@ class UdpSocket
 {
     const DATAGRAM_MAX_LENGTH = 65023;
 
+    /** @var string */
     protected $ip;
+    /** @var int */
     protected $port;
-
     /** @var resource|null */
     protected $socket;
 
-    public function __construct($ip, $port = 514)
+    public function __construct(string $ip, int $port = 514)
     {
         $this->ip = $ip;
         $this->port = $port;
@@ -33,7 +34,7 @@ class UdpSocket
         $this->send($this->assembleMessage($line, $header));
     }
 
-    public function close()
+    public function close(): void
     {
         if (is_resource($this->socket)) {
             socket_close($this->socket);
@@ -41,7 +42,7 @@ class UdpSocket
         }
     }
 
-    protected function send($chunk)
+    protected function send(string $chunk): void
     {
         if (!is_resource($this->socket)) {
             throw new \RuntimeException('The UdpSocket to '.$this->ip.':'.$this->port.' has been closed and can not be written to anymore');
@@ -49,7 +50,7 @@ class UdpSocket
         socket_sendto($this->socket, $chunk, strlen($chunk), $flags = 0, $this->ip, $this->port);
     }
 
-    protected function assembleMessage($line, $header)
+    protected function assembleMessage(string $line, string $header): string
     {
         $chunkSize = self::DATAGRAM_MAX_LENGTH - strlen($header);
 
diff --git a/src/Monolog/Handler/SyslogUdpHandler.php b/src/Monolog/Handler/SyslogUdpHandler.php
index dc844020..103206bb 100644
--- a/src/Monolog/Handler/SyslogUdpHandler.php
+++ b/src/Monolog/Handler/SyslogUdpHandler.php
@@ -32,7 +32,7 @@ class SyslogUdpHandler extends AbstractSyslogHandler
      * @param bool   $bubble   Whether the messages that are handled can bubble up the stack or not
      * @param string $ident    Program name or tag for each log message.
      */
-    public function __construct($host, $port = 514, $facility = LOG_USER, $level = Logger::DEBUG, $bubble = true, $ident = 'php')
+    public function __construct($host, $port = 514, $facility = LOG_USER, $level = Logger::DEBUG, bool $bubble = true, $ident = 'php')
     {
         parent::__construct($facility, $level, $bubble);
 
@@ -41,7 +41,7 @@ class SyslogUdpHandler extends AbstractSyslogHandler
         $this->socket = new UdpSocket($host, $port ?: 514);
     }
 
-    protected function write(array $record)
+    protected function write(array $record): void
     {
         $lines = $this->splitMessageIntoLines($record['formatted']);
 
@@ -52,7 +52,7 @@ class SyslogUdpHandler extends AbstractSyslogHandler
         }
     }
 
-    public function close()
+    public function close(): void
     {
         $this->socket->close();
     }
diff --git a/src/Monolog/Handler/TestHandler.php b/src/Monolog/Handler/TestHandler.php
index 55c48334..db9174e2 100644
--- a/src/Monolog/Handler/TestHandler.php
+++ b/src/Monolog/Handler/TestHandler.php
@@ -138,7 +138,7 @@ class TestHandler extends AbstractProcessingHandler
     /**
      * {@inheritdoc}
      */
-    protected function write(array $record)
+    protected function write(array $record): void
     {
         $this->recordsByLevel[$record['level']][] = $record;
         $this->records[] = $record;
diff --git a/src/Monolog/Handler/WhatFailureGroupHandler.php b/src/Monolog/Handler/WhatFailureGroupHandler.php
index c2a58d5d..5c1f86b1 100644
--- a/src/Monolog/Handler/WhatFailureGroupHandler.php
+++ b/src/Monolog/Handler/WhatFailureGroupHandler.php
@@ -44,7 +44,7 @@ class WhatFailureGroupHandler extends GroupHandler
     /**
      * {@inheritdoc}
      */
-    public function handleBatch(array $records)
+    public function handleBatch(array $records): void
     {
         if ($this->processors) {
             $processed = array();
diff --git a/src/Monolog/Handler/ZendMonitorHandler.php b/src/Monolog/Handler/ZendMonitorHandler.php
index c0bceb42..95eca6d5 100644
--- a/src/Monolog/Handler/ZendMonitorHandler.php
+++ b/src/Monolog/Handler/ZendMonitorHandler.php
@@ -45,7 +45,7 @@ class ZendMonitorHandler extends AbstractProcessingHandler
      * @param  bool                      $bubble
      * @throws MissingExtensionException
      */
-    public function __construct($level = Logger::DEBUG, $bubble = true)
+    public function __construct($level = Logger::DEBUG, bool $bubble = true)
     {
         if (!function_exists('zend_monitor_custom_event')) {
             throw new MissingExtensionException('You must have Zend Server installed in order to use this handler');
@@ -56,7 +56,7 @@ class ZendMonitorHandler extends AbstractProcessingHandler
     /**
      * {@inheritdoc}
      */
-    protected function write(array $record)
+    protected function write(array $record): void
     {
         $this->writeZendMonitorCustomEvent(
             $this->levelMap[$record['level']],
@@ -65,14 +65,7 @@ class ZendMonitorHandler extends AbstractProcessingHandler
         );
     }
 
-    /**
-     * Write a record to Zend Monitor
-     *
-     * @param int    $level
-     * @param string $message
-     * @param array  $formatted
-     */
-    protected function writeZendMonitorCustomEvent($level, $message, $formatted)
+    protected function writeZendMonitorCustomEvent(int $level, string $message, array $formatted)
     {
         zend_monitor_custom_event($level, $message, $formatted);
     }
@@ -85,12 +78,7 @@ class ZendMonitorHandler extends AbstractProcessingHandler
         return new NormalizerFormatter();
     }
 
-    /**
-     * Get the level map
-     *
-     * @return array
-     */
-    public function getLevelMap()
+    public function getLevelMap(): array
     {
         return $this->levelMap;
     }
diff --git a/src/Monolog/Logger.php b/src/Monolog/Logger.php
index a22bf7ec..c44959f6 100644
--- a/src/Monolog/Logger.php
+++ b/src/Monolog/Logger.php
@@ -135,7 +135,7 @@ class Logger implements LoggerInterface
     protected $timezone;
 
     /**
-     * @var callable
+     * @var ?callable
      */
     protected $exceptionHandler;
 
@@ -143,9 +143,9 @@ class Logger implements LoggerInterface
      * @param string             $name       The logging channel, a simple descriptive name that is attached to all log records
      * @param HandlerInterface[] $handlers   Optional stack of handlers, the first one in the array is called first, etc.
      * @param callable[]         $processors Optional array of processors
-     * @param DateTimeZone       $timezone   Optional timezone, if not provided date_default_timezone_get() will be used
+     * @param ?DateTimeZone      $timezone   Optional timezone, if not provided date_default_timezone_get() will be used
      */
-    public function __construct(string $name, array $handlers = [], array $processors = [], DateTimeZone $timezone = null)
+    public function __construct(string $name, array $handlers = [], array $processors = [], ?DateTimeZone $timezone = null)
     {
         $this->name = $name;
         $this->setHandlers($handlers);
@@ -360,7 +360,7 @@ class Logger implements LoggerInterface
     /**
      * Converts PSR-3 levels to Monolog ones if necessary
      *
-     * @param string|int Level number (monolog) or name (PSR-3)
+     * @param  string|int                        $level Level number (monolog) or name (PSR-3)
      * @throws \Psr\Log\InvalidArgumentException If level is not defined
      */
     public static function toMonologLevel($level): int
diff --git a/src/Monolog/Processor/PsrLogMessageProcessor.php b/src/Monolog/Processor/PsrLogMessageProcessor.php
index 7311c2be..ef8c4b2e 100644
--- a/src/Monolog/Processor/PsrLogMessageProcessor.php
+++ b/src/Monolog/Processor/PsrLogMessageProcessor.php
@@ -22,16 +22,17 @@ class PsrLogMessageProcessor
 {
     const SIMPLE_DATE = "Y-m-d\TH:i:s.uP";
 
+    /** @var ?string */
     private $dateFormat;
 
     /** @var bool */
     private $removeUsedContextFields;
 
     /**
-     * @param string $dateFormat              The format of the timestamp: one supported by DateTime::format
-     * @param bool   $removeUsedContextFields If set to true the fields interpolated into message gets unset
+     * @param ?string $dateFormat              The format of the timestamp: one supported by DateTime::format
+     * @param bool    $removeUsedContextFields If set to true the fields interpolated into message gets unset
      */
-    public function __construct(string $dateFormat = null, bool $removeUsedContextFields = false)
+    public function __construct(?string $dateFormat = null, bool $removeUsedContextFields = false)
     {
         $this->dateFormat = $dateFormat;
         $this->removeUsedContextFields = $removeUsedContextFields;
diff --git a/src/Monolog/Test/TestCase.php b/src/Monolog/Test/TestCase.php
index 23cf9add..ecb8907f 100644
--- a/src/Monolog/Test/TestCase.php
+++ b/src/Monolog/Test/TestCase.php
@@ -25,10 +25,10 @@ class TestCase extends \PHPUnit\Framework\TestCase
     /**
      * @return array Record
      */
-    protected function getRecord($level = Logger::WARNING, $message = 'test', $context = [])
+    protected function getRecord($level = Logger::WARNING, $message = 'test', array $context = []): array
     {
         return [
-            'message' => $message,
+            'message' => (string) $message,
             'context' => $context,
             'level' => $level,
             'level_name' => Logger::getLevelName($level),
@@ -38,10 +38,7 @@ class TestCase extends \PHPUnit\Framework\TestCase
         ];
     }
 
-    /**
-     * @return array
-     */
-    protected function getMultipleRecords()
+    protected function getMultipleRecords(): array
     {
         return [
             $this->getRecord(Logger::DEBUG, 'debug message 1'),
@@ -52,6 +49,9 @@ class TestCase extends \PHPUnit\Framework\TestCase
         ];
     }
 
+    /**
+     * @suppress PhanTypeMismatchReturn
+     */
     protected function getIdentityFormatter(): FormatterInterface
     {
         $formatter = $this->createMock(FormatterInterface::class);
diff --git a/tests/Monolog/Handler/HandlerWrapperTest.php b/tests/Monolog/Handler/HandlerWrapperTest.php
index bedc1750..42fff1c6 100644
--- a/tests/Monolog/Handler/HandlerWrapperTest.php
+++ b/tests/Monolog/Handler/HandlerWrapperTest.php
@@ -82,9 +82,8 @@ class HandlerWrapperTest extends TestCase
         $records = $this->getMultipleRecords();
         $this->handler->expects($this->once())
             ->method('handleBatch')
-            ->with($records)
-            ->willReturn($result);
+            ->with($records);
 
-        $this->assertEquals($result, $this->wrapper->handleBatch($records));
+        $this->wrapper->handleBatch($records);
     }
 }
diff --git a/tests/Monolog/Handler/SyslogUdpHandlerTest.php b/tests/Monolog/Handler/SyslogUdpHandlerTest.php
index 9f32d910..c35b3318 100644
--- a/tests/Monolog/Handler/SyslogUdpHandlerTest.php
+++ b/tests/Monolog/Handler/SyslogUdpHandlerTest.php
@@ -44,7 +44,7 @@ class SyslogUdpHandlerTest extends TestCase
 
         $socket = $this->getMockBuilder('Monolog\Handler\SyslogUdp\UdpSocket')
             ->setMethods(['write'])
-            ->setConstructorArgs(['lol', 'lol'])
+            ->setConstructorArgs(['lol'])
             ->getMock();
         $socket->expects($this->at(0))
             ->method('write')
@@ -65,7 +65,7 @@ class SyslogUdpHandlerTest extends TestCase
 
         $socket = $this->getMockBuilder('Monolog\Handler\SyslogUdp\UdpSocket')
             ->setMethods(['write'])
-            ->setConstructorArgs(['lol', 'lol'])
+            ->setConstructorArgs(['lol'])
             ->getMock();
         $socket->expects($this->never())
             ->method('write');
diff --git a/tests/Monolog/Handler/UdpSocketTest.php b/tests/Monolog/Handler/UdpSocketTest.php
index 1adf79a0..bc01a25b 100644
--- a/tests/Monolog/Handler/UdpSocketTest.php
+++ b/tests/Monolog/Handler/UdpSocketTest.php
@@ -23,7 +23,7 @@ class UdpSocketTest extends TestCase
     {
         $socket = $this->getMockBuilder('Monolog\Handler\SyslogUdp\UdpSocket')
             ->setMethods(['send'])
-            ->setConstructorArgs(['lol', 'lol'])
+            ->setConstructorArgs(['lol'])
             ->getMock();
 
         $socket->expects($this->at(0))
@@ -37,7 +37,7 @@ class UdpSocketTest extends TestCase
     {
         $socket = $this->getMockBuilder('Monolog\Handler\SyslogUdp\UdpSocket')
             ->setMethods(['send'])
-            ->setConstructorArgs(['lol', 'lol'])
+            ->setConstructorArgs(['lol'])
             ->getMock();
 
         $truncatedString = str_repeat("derp", 16254).'d';