diff --git a/lib/Doctrine/ORM/Mapping/Driver/AnnotationDriver.php b/lib/Doctrine/ORM/Mapping/Driver/AnnotationDriver.php
index cb30e1cbf..a29b832ac 100644
--- a/lib/Doctrine/ORM/Mapping/Driver/AnnotationDriver.php
+++ b/lib/Doctrine/ORM/Mapping/Driver/AnnotationDriver.php
@@ -41,7 +41,7 @@ class AnnotationDriver implements Driver
      *
      * @var AnnotationReader
      */
-    private $_reader;
+    protected $_reader;
 
     /**
      * The paths where to look for mapping files.