diff --git a/src/Monolog/Formatter/HtmlFormatter.php b/src/Monolog/Formatter/HtmlFormatter.php
index 54b84618..90db3f2a 100644
--- a/src/Monolog/Formatter/HtmlFormatter.php
+++ b/src/Monolog/Formatter/HtmlFormatter.php
@@ -93,7 +93,7 @@ class HtmlFormatter extends NormalizerFormatter
         if ($record['context']) {
             $embeddedTable = '<table cellspacing="1" width="100%">';
             foreach ($record['context'] as $key => $value) {
-                $embeddedTable .= $this->addRow((string)$key, $this->convertToString($value));
+                $embeddedTable .= $this->addRow((string) $key, $this->convertToString($value));
             }
             $embeddedTable .= '</table>';
             $output .= $this->addRow('Context', $embeddedTable, false);
@@ -101,7 +101,7 @@ class HtmlFormatter extends NormalizerFormatter
         if ($record['extra']) {
             $embeddedTable = '<table cellspacing="1" width="100%">';
             foreach ($record['extra'] as $key => $value) {
-                $embeddedTable .= $this->addRow((string)$key, $this->convertToString($value));
+                $embeddedTable .= $this->addRow((string) $key, $this->convertToString($value));
             }
             $embeddedTable .= '</table>';
             $output .= $this->addRow('Extra', $embeddedTable, false);
diff --git a/src/Monolog/Formatter/JsonFormatter.php b/src/Monolog/Formatter/JsonFormatter.php
index 454b6976..c367baa6 100644
--- a/src/Monolog/Formatter/JsonFormatter.php
+++ b/src/Monolog/Formatter/JsonFormatter.php
@@ -11,7 +11,6 @@
 
 namespace Monolog\Formatter;
 
-use Monolog\Utils;
 use Throwable;
 
 /**
diff --git a/src/Monolog/Formatter/NormalizerFormatter.php b/src/Monolog/Formatter/NormalizerFormatter.php
index 779e18bb..3fdb3b45 100644
--- a/src/Monolog/Formatter/NormalizerFormatter.php
+++ b/src/Monolog/Formatter/NormalizerFormatter.php
@@ -203,7 +203,7 @@ class NormalizerFormatter implements FormatterInterface
             }
 
             if (isset($e->detail)) {
-                if  (is_string($e->detail)) {
+                if (is_string($e->detail)) {
                     $data['detail'] = $e->detail;
                 } elseif (is_object($e->detail) || is_array($e->detail)) {
                     $data['detail'] = $this->toJson($e->detail, true);
@@ -230,7 +230,7 @@ class NormalizerFormatter implements FormatterInterface
      *
      * @param  mixed             $data
      * @throws \RuntimeException if encoding fails and errors are not ignored
-     * @return string if encoding fails and ignoreErrors is true 'null' is returned
+     * @return string            if encoding fails and ignoreErrors is true 'null' is returned
      */
     protected function toJson($data, bool $ignoreErrors = false): string
     {
diff --git a/src/Monolog/Handler/FallbackGroupHandler.php b/src/Monolog/Handler/FallbackGroupHandler.php
index ea065748..9c92fa2d 100644
--- a/src/Monolog/Handler/FallbackGroupHandler.php
+++ b/src/Monolog/Handler/FallbackGroupHandler.php
@@ -31,6 +31,7 @@ class FallbackGroupHandler extends GroupHandler
                 // What throwable?
             }
         }
+
         return false === $this->bubble;
     }
 
diff --git a/src/Monolog/Handler/ZendMonitorHandler.php b/src/Monolog/Handler/ZendMonitorHandler.php
index d664fa89..78a886f1 100644
--- a/src/Monolog/Handler/ZendMonitorHandler.php
+++ b/src/Monolog/Handler/ZendMonitorHandler.php
@@ -71,10 +71,10 @@ class ZendMonitorHandler extends AbstractProcessingHandler
 
     /**
      * Write to Zend Monitor Events
-     * @param string $type Text displayed in "Class Name (custom)" field
-     * @param string $message Text displayed in "Error String"
-     * @param mixed $formatted Displayed in Custom Variables tab
-     * @param int $severity Set the event severity level (-1,0,1)
+     * @param string $type      Text displayed in "Class Name (custom)" field
+     * @param string $message   Text displayed in "Error String"
+     * @param mixed  $formatted Displayed in Custom Variables tab
+     * @param int    $severity  Set the event severity level (-1,0,1)
      */
     protected function writeZendMonitorCustomEvent(string $type, string $message, array $formatted, int $severity): void
     {
diff --git a/src/Monolog/Utils.php b/src/Monolog/Utils.php
index a6977b92..007ad686 100644
--- a/src/Monolog/Utils.php
+++ b/src/Monolog/Utils.php
@@ -66,10 +66,10 @@ final class Utils
      * Return the JSON representation of a value
      *
      * @param  mixed             $data
-     * @param  int               $encodeFlags flags to pass to json encode, defaults to JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE
+     * @param  int               $encodeFlags  flags to pass to json encode, defaults to JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE
      * @param  bool              $ignoreErrors whether to ignore encoding errors or to throw on error, when ignored and the encoding fails, "null" is returned which is valid json for null
      * @throws \RuntimeException if encoding fails and errors are not ignored
-     * @return string when errors are ignored and the encoding fails, "null" is returned which is valid json for null
+     * @return string            when errors are ignored and the encoding fails, "null" is returned which is valid json for null
      */
     public static function jsonEncode($data, ?int $encodeFlags = null, bool $ignoreErrors = false): string
     {
@@ -102,8 +102,8 @@ final class Utils
      * initial error is not encoding related or the input can't be cleaned then
      * raise a descriptive exception.
      *
-     * @param  int               $code return code of json_last_error function
-     * @param  mixed             $data data that was meant to be encoded
+     * @param  int               $code        return code of json_last_error function
+     * @param  mixed             $data        data that was meant to be encoded
      * @param  int               $encodeFlags flags to pass to json encode, defaults to JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE | JSON_PRESERVE_ZERO_FRACTION
      * @throws \RuntimeException if failure can't be corrected
      * @return string            JSON encoded data after error correction
diff --git a/tests/Monolog/ErrorHandlerTest.php b/tests/Monolog/ErrorHandlerTest.php
index 8cc591da..69cb3e50 100644
--- a/tests/Monolog/ErrorHandlerTest.php
+++ b/tests/Monolog/ErrorHandlerTest.php
@@ -28,7 +28,8 @@ class ErrorHandlerTest extends \PHPUnit\Framework\TestCase
         $logger = new Logger('test', [$handler = new TestHandler]);
         $errHandler = new ErrorHandler($logger);
 
-        $phpunitHandler = set_error_handler($prevHandler = function() {});
+        $phpunitHandler = set_error_handler($prevHandler = function () {
+        });
 
         try {
             $errHandler->registerErrorHandler([], true);
diff --git a/tests/Monolog/Handler/NativeMailerHandlerTest.php b/tests/Monolog/Handler/NativeMailerHandlerTest.php
index 0803f5b4..62f79b20 100644
--- a/tests/Monolog/Handler/NativeMailerHandlerTest.php
+++ b/tests/Monolog/Handler/NativeMailerHandlerTest.php
@@ -13,7 +13,6 @@ namespace Monolog\Handler;
 
 use Monolog\Test\TestCase;
 use Monolog\Logger;
-use InvalidArgumentException;
 
 function mail($to, $subject, $message, $additional_headers = null, $additional_parameters = null)
 {
diff --git a/tests/Monolog/UtilsTest.php b/tests/Monolog/UtilsTest.php
index c74b96eb..68a62b14 100644
--- a/tests/Monolog/UtilsTest.php
+++ b/tests/Monolog/UtilsTest.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 /*
  * This file is part of the Monolog package.