diff --git a/lib/Doctrine/ORM/Internal/Hydration/AbstractHydrator.php b/lib/Doctrine/ORM/Internal/Hydration/AbstractHydrator.php
index f430cb912..7c7e2ef81 100644
--- a/lib/Doctrine/ORM/Internal/Hydration/AbstractHydrator.php
+++ b/lib/Doctrine/ORM/Internal/Hydration/AbstractHydrator.php
@@ -297,8 +297,9 @@ abstract class AbstractHydrator
                     if(
                         isset($cacheKeyInfo['discriminatorColumn']) && 
                         isset($data[$cacheKeyInfo['discriminatorColumn']]) &&
+                        // Note: loose comparison required. See https://github.com/doctrine/doctrine2/pull/6304#issuecomment-323294442
                         $data[$cacheKeyInfo['discriminatorColumn']] != $cacheKeyInfo['discriminatorValue']
-                    ){
+                    ) {
                         break;
                     }