Index: modules/user/user.admin.inc
===================================================================
RCS file: /cvs/drupal/drupal/modules/user/user.admin.inc,v
retrieving revision 1.62
diff -u -p -r1.62 user.admin.inc
--- modules/user/user.admin.inc	5 Jul 2009 18:07:04 -0000	1.62
+++ modules/user/user.admin.inc	6 Jul 2009 15:05:24 -0000
@@ -952,9 +952,11 @@ function user_modules_installed($modules
 function user_modules_uninstalled($modules) {
   $permissions = array();
   foreach ($modules as $module) {
-    $permissions = array_merge($permissions, array_keys(module_invoke($module, 'permission')));
+    if (drupal_function_exists($module . '_permission')) {
+      $permissions = array_merge($permissions, array_keys(module_invoke($module, 'permission')));
+    }
   }
-  if (!empty($permissions)) {
+  if (!empty($permissions)) {
     db_delete('role_permission')
       ->condition('permission', $permissions, 'IN')
       ->execute();