diff --git a/Test/ConstraintValidatorTestCase.php b/Test/ConstraintValidatorTestCase.php
index ea07316ac..3d1fc81c9 100644
--- a/Test/ConstraintValidatorTestCase.php
+++ b/Test/ConstraintValidatorTestCase.php
@@ -341,6 +341,9 @@ private function getViolation()
     }
 }
 
+/**
+ * @internal
+ */
 class AssertingContextualValidator implements ContextualValidatorInterface
 {
     private $expectNoValidate = false;