diff --git a/pkg/async-event-dispatcher/EventTransformer.php b/pkg/async-event-dispatcher/EventTransformer.php
index 6b6aa0f39..abb67566f 100644
--- a/pkg/async-event-dispatcher/EventTransformer.php
+++ b/pkg/async-event-dispatcher/EventTransformer.php
@@ -13,7 +13,7 @@ interface EventTransformer
      *
      * @return Message
      */
-    public function toMessage($eventName, Event $event);
+    public function toMessage($eventName, Event $event = null);
 
     /**
      * If you able to transform message back to event return it.
diff --git a/pkg/enqueue-bundle/Tests/Functional/App/TestAsyncEventTransformer.php b/pkg/enqueue-bundle/Tests/Functional/App/TestAsyncEventTransformer.php
index 63d6df75a..4293ab85e 100644
--- a/pkg/enqueue-bundle/Tests/Functional/App/TestAsyncEventTransformer.php
+++ b/pkg/enqueue-bundle/Tests/Functional/App/TestAsyncEventTransformer.php
@@ -24,7 +24,7 @@ public function __construct(Context $context)
         $this->context = $context;
     }
 
-    public function toMessage($eventName, Event $event)
+    public function toMessage($eventName, Event $event = null)
     {
         if (Event::class === get_class($event)) {
             return $this->context->createMessage(json_encode(''));