diff --git a/src/Symfony/Component/EventDispatcher/EventDispatcher.php b/src/Symfony/Component/EventDispatcher/EventDispatcher.php
index ebfd1ec6d5e7d..f7c66309827a4 100644
--- a/src/Symfony/Component/EventDispatcher/EventDispatcher.php
+++ b/src/Symfony/Component/EventDispatcher/EventDispatcher.php
@@ -54,7 +54,7 @@ public function dispatch($event/*, string $eventName = null*/)
 
         if (\is_object($event)) {
             $eventName = $eventName ?? \get_class($event);
-        } elseif (\is_string($event) && (null === $eventName || $eventName instanceof Event)) {
+        } elseif (\is_string($event) && (null === $eventName || $eventName instanceof ContractsEvent || $eventName instanceof Event)) {
             @trigger_error(sprintf('Calling the "%s::dispatch()" method with the event name as the first argument is deprecated since Symfony 4.3, pass it as the second argument and provide the event object as the first argument instead.', EventDispatcherInterface::class), E_USER_DEPRECATED);
             $swap = $event;
             $event = $eventName ?? new Event();
diff --git a/src/Symfony/Component/EventDispatcher/LegacyEventDispatcherProxy.php b/src/Symfony/Component/EventDispatcher/LegacyEventDispatcherProxy.php
index be0d381a29be6..003de2efddafd 100644
--- a/src/Symfony/Component/EventDispatcher/LegacyEventDispatcherProxy.php
+++ b/src/Symfony/Component/EventDispatcher/LegacyEventDispatcherProxy.php
@@ -59,7 +59,7 @@ public function dispatch($event/*, string $eventName = null*/)
 
         if (\is_object($event)) {
             $eventName = $eventName ?? \get_class($event);
-        } elseif (\is_string($event) && (null === $eventName || $eventName instanceof Event)) {
+        } elseif (\is_string($event) && (null === $eventName || $eventName instanceof ContractsEvent || $eventName instanceof Event)) {
             @trigger_error(sprintf('Calling the "%s::dispatch()" method with the event name as the first argument is deprecated since Symfony 4.3, pass it as the second argument and provide the event object as the first argument instead.', ContractsEventDispatcherInterface::class), E_USER_DEPRECATED);
             $swap = $event;
             $event = $eventName ?? new Event();