diff --git a/modules/system/system.api.php b/modules/system/system.api.php
index d2821e0..b44fa99 100644
--- a/modules/system/system.api.php
+++ b/modules/system/system.api.php
@@ -206,6 +206,7 @@ function hook_entity_info() {
         'id' => 'nid',
         'revision' => 'vid',
         'bundle' => 'type',
+        'language' => 'language',
       ),
       'bundle keys' => array(
         'bundle' => 'type',