diff --git a/mercure.rst b/mercure.rst
index cebcc11eeb0..f6250e90c61 100644
--- a/mercure.rst
+++ b/mercure.rst
@@ -551,9 +551,10 @@ be handled by a stub publisher::
     // tests/Functional/Fixtures/PublisherStub.php
     namespace App\Tests\Functional\Fixtures;
 
+    use Symfony\Component\Mercure\PublisherInterface;
     use Symfony\Component\Mercure\Update;
 
-    class PublisherStub
+    class PublisherStub implements PublisherInterface
     {
         public function __invoke(Update $update): string
         {