diff --git a/src/Monolog/Handler/ErrorLogHandler.php b/src/Monolog/Handler/ErrorLogHandler.php
index 7ab0f2e4..cc7dbb10 100644
--- a/src/Monolog/Handler/ErrorLogHandler.php
+++ b/src/Monolog/Handler/ErrorLogHandler.php
@@ -38,7 +38,7 @@ class ErrorLogHandler extends AbstractProcessingHandler
     {
         parent::__construct($level, $bubble);
 
-        if (false === in_array($messageType, self::getAvailableTypes())) {
+        if (false === in_array($messageType, self::getAvailableTypes(), true)) {
             $message = sprintf('The given message type "%s" is not supported', print_r($messageType, true));
             throw new \InvalidArgumentException($message);
         }