diff --git a/lib/Doctrine/ORM/Mapping/ClassMetadataFactory.php b/lib/Doctrine/ORM/Mapping/ClassMetadataFactory.php
index 248e4a2f9..239022b0f 100644
--- a/lib/Doctrine/ORM/Mapping/ClassMetadataFactory.php
+++ b/lib/Doctrine/ORM/Mapping/ClassMetadataFactory.php
@@ -494,6 +494,10 @@ class ClassMetadataFactory implements ClassMetadataFactoryInterface
      */
     public function isTransient($class)
     {
+        if ( ! $this->initialized) {
+            $this->initialize();
+        }
+        
         return $this->driver->isTransient($class);
     }
 }