diff --git a/lib/Doctrine/ORM/Mapping/ClassMetadataInfo.php b/lib/Doctrine/ORM/Mapping/ClassMetadataInfo.php
index d828335ca..53eedacca 100644
--- a/lib/Doctrine/ORM/Mapping/ClassMetadataInfo.php
+++ b/lib/Doctrine/ORM/Mapping/ClassMetadataInfo.php
@@ -2203,11 +2203,11 @@ class ClassMetadataInfo implements ClassMetadata
             $overrideMapping['id'] = $mapping['id'];
         }
 
-        if ( ! isset($overrideMapping['type']) || $overrideMapping['type'] === null) {
+        if ( ! isset($overrideMapping['type'])) {
             $overrideMapping['type'] = $mapping['type'];
         }
 
-        if ( ! isset($overrideMapping['fieldName']) || $overrideMapping['fieldName'] === null) {
+        if ( ! isset($overrideMapping['fieldName'])) {
             $overrideMapping['fieldName'] = $mapping['fieldName'];
         }