Index: modules/user/user.admin.inc
===================================================================
RCS file: /cvs/drupal/drupal/modules/user/user.admin.inc,v
retrieving revision 1.87
diff -u -r1.87 user.admin.inc
--- modules/user/user.admin.inc	27 Oct 2009 04:08:42 -0000	1.87
+++ modules/user/user.admin.inc	31 Oct 2009 06:00:11 -0000
@@ -820,7 +820,7 @@
     drupal_set_message(t('The role has been renamed.'));
   }
   elseif ($form_state['values']['op'] == t('Delete role')) {
-    user_role_delete($form_state['values']['rid']);
+    user_role_delete((int)$form_state['values']['rid']);
     drupal_set_message(t('The role has been deleted.'));
   }
   elseif ($form_state['values']['op'] == t('Add role')) {