diff --git a/lib/Doctrine/Common/Persistence/Mapping/AbstractClassMetadataFactory.php b/lib/Doctrine/Common/Persistence/Mapping/AbstractClassMetadataFactory.php
index 01ad58fd0..9c56bb43f 100644
--- a/lib/Doctrine/Common/Persistence/Mapping/AbstractClassMetadataFactory.php
+++ b/lib/Doctrine/Common/Persistence/Mapping/AbstractClassMetadataFactory.php
@@ -52,7 +52,7 @@ abstract class AbstractClassMetadataFactory implements ClassMetadataFactory
     /**
      * @var array
      */
-    private $loadedMetadata = array();
+    protected $loadedMetadata = array();
 
     /**
      * @var bool