diff --git a/src/Symfony/Component/Serializer/Normalizer/CustomNormalizer.php b/src/Symfony/Component/Serializer/Normalizer/CustomNormalizer.php
index bc3d432de5..e3f09a9436 100644
--- a/src/Symfony/Component/Serializer/Normalizer/CustomNormalizer.php
+++ b/src/Symfony/Component/Serializer/Normalizer/CustomNormalizer.php
@@ -59,10 +59,6 @@ class CustomNormalizer extends SerializerAwareNormalizer implements NormalizerIn
      */
     public function supportsDenormalization($data, $type, $format = null)
     {
-        if (PHP_VERSION_ID < 50307) {
-            return class_exists($type) && in_array('Symfony\Component\Serializer\Normalizer\DenormalizableInterface', class_implements($type), true);
-        }
-
         return is_subclass_of($type, 'Symfony\Component\Serializer\Normalizer\DenormalizableInterface');
     }
 }