diff --git a/includes/cache.inc b/includes/cache.inc
index e7982835afd844e36e38c9f539a36db517616636..c33961a449ec228b99f7e323f744118a44bcfc20 100644
--- a/includes/cache.inc
+++ b/includes/cache.inc
@@ -1,4 +1,5 @@
 <?php
+// $Id$
 
 /**
  * Return data from the persistent cache.