diff --git a/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/FrameworkExtension.php b/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/FrameworkExtension.php
index a95bf273aa..af080b562c 100644
--- a/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/FrameworkExtension.php
+++ b/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/FrameworkExtension.php
@@ -299,9 +299,14 @@ class FrameworkExtension extends Extension
 
         $this->addClassesToCompile(array(
             'Symfony\\Component\\HttpFoundation\\SessionStorage\\SessionStorageInterface',
-            $container->findDefinition('session.storage')->getClass(),
             $container->getDefinition('session')->getClass(),
         ));
+
+        if ($container->hasDefinition($config['storage_id'])) {
+            $this->addClassesToCompile(array(
+                $container->findDefinition('session.storage')->getClass(),
+            ));
+        }
     }
 
     /**