diff --git a/src/Dispatch/EventDispatcherInterface.php b/src/Dispatch/EventDispatcherInterface.php
index a9a962d..d6bb146 100644
--- a/src/Dispatch/EventDispatcherInterface.php
+++ b/src/Dispatch/EventDispatcherInterface.php
@@ -25,5 +25,5 @@ public function removeListener(string $eventName, EventHandlerInterface $listene
      * @param object $eventContext
      * @param string|null $eventName
      */
-    public function dispatch(object $eventContext, string $eventName = null): void;
+    public function dispatch(object $eventContext, ?string $eventName = null): void;
 }
diff --git a/src/Symfony/Event.php b/src/Symfony/Event.php
index 5b9328a..fb6401a 100644
--- a/src/Symfony/Event.php
+++ b/src/Symfony/Event.php
@@ -20,7 +20,7 @@ class Event implements EventContextInterface
      * @param string $action
      * @param array $properties
      */
-    public function __construct(string $action = null, array $properties = [])
+    public function __construct(?string $action = null, array $properties = [])
     {
         $this->event = new GenericEvent($action, $properties);
     }
diff --git a/tests/Dispatch/MockBackend.php b/tests/Dispatch/MockBackend.php
index b7d0d5a..f4bfe22 100644
--- a/tests/Dispatch/MockBackend.php
+++ b/tests/Dispatch/MockBackend.php
@@ -11,7 +11,7 @@ class MockBackend implements EventDispatcherInterface
 
     public $listeners = [];
 
-    public function dispatch(object $eventContext, string $eventName = null): void
+    public function dispatch(object $eventContext, ?string $eventName = null): void
     {
         $listeners = $this->listeners[$eventName] ?? [];
         foreach ($listeners as $listener) {