diff --git a/src/Symfony/Component/EventDispatcher/LegacyEventDispatcherProxy.php b/src/Symfony/Component/EventDispatcher/LegacyEventDispatcherProxy.php
index 86917b7d5438f..3ae3735e23e52 100644
--- a/src/Symfony/Component/EventDispatcher/LegacyEventDispatcherProxy.php
+++ b/src/Symfony/Component/EventDispatcher/LegacyEventDispatcherProxy.php
@@ -58,13 +58,13 @@ public function dispatch($event/*, string $eventName = null*/)
         if (\is_object($event)) {
             $eventName = $eventName ?? \get_class($event);
         } else {
-            @trigger_error(sprintf('Calling the "%s::dispatch()" method with the event name as first argument is deprecated since Symfony 4.3, pass it second and provide the event object first instead.', EventDispatcherInterface::class), E_USER_DEPRECATED);
+            @trigger_error(sprintf('Calling the "%s::dispatch()" method with the event name as first argument is deprecated since Symfony 4.3, pass it second and provide the event object first instead.', ContractsEventDispatcherInterface::class), E_USER_DEPRECATED);
             $swap = $event;
             $event = $eventName ?? new Event();
             $eventName = $swap;
 
             if (!$event instanceof Event) {
-                throw new \TypeError(sprintf('Argument 1 passed to "%s::dispatch()" must be an instance of %s, %s given.', EventDispatcherInterface::class, Event::class, \is_object($event) ? \get_class($event) : \gettype($event)));
+                throw new \TypeError(sprintf('Argument 1 passed to "%s::dispatch()" must be an instance of %s, %s given.', ContractsEventDispatcherInterface::class, Event::class, \is_object($event) ? \get_class($event) : \gettype($event)));
             }
         }