diff --git a/tests/Serializer/Doctrine/IntegrationTest.php b/tests/Serializer/Doctrine/IntegrationTest.php
index cd6ee84d7..fcee0228a 100644
--- a/tests/Serializer/Doctrine/IntegrationTest.php
+++ b/tests/Serializer/Doctrine/IntegrationTest.php
@@ -69,6 +69,7 @@ public function testDiscriminatorIsInferredFromDoctrine()
         $class = new Clazz($teacher, [$student1, $student2]);
 
         $em->persist($teacher);
+        $em->flush();
         $em->persist($student1);
         $em->persist($student2);
         $em->persist($class);