diff --git a/metatags_quick.install b/metatags_quick.install
index e62c0ab..2db27a0 100644
--- a/metatags_quick.install
+++ b/metatags_quick.install
@@ -119,5 +119,7 @@ function metatags_quick_update_7004() {
    * syntax, so it should work.
    */
   db_query('ALTER TABLE {metatags_quick_path_based} DROP PRIMARY KEY, ADD PRIMARY KEY (`id`)');
-  db_add_unique_key('metatags_quick_path_based', 'lang_path', array('lang', 'path'));
+  if (!db_index_exists('metatags_quick_path_based', 'lang_path')) {
+    db_add_unique_key('metatags_quick_path_based', 'lang_path', array('lang', 'path'));
+  }
 }