Index: privatemsg.install
===================================================================
RCS file: /cvs/drupal-contrib/contributions/modules/privatemsg/privatemsg.install,v
retrieving revision 1.5.2.4.2.11.2.11.2.13
diff -u -p -r1.5.2.4.2.11.2.11.2.13 privatemsg.install
--- privatemsg.install	18 Dec 2010 14:35:48 -0000	1.5.2.4.2.11.2.11.2.13
+++ privatemsg.install	2 Jan 2011 11:33:28 -0000
@@ -150,8 +150,10 @@ function privatemsg_uninstall() {
  * Implements hook_update_dependencies().
  */
 function privatemsg_update_dependencies() {
-  $dependencies['privatemsg']['7004']['privatemsg_filter'] = '7001';
-  return $dependencies;
+  if (module_exists('privatemsg_filter')) {
+    $dependencies['privatemsg']['7004']['privatemsg_filter'] = '7001';
+    return $dependencies;
+  }
 }
 
 /**