diff --git a/backup/db/mysql.php b/backup/db/mysql.php
index b9eda335d4f..c54492ae493 100644
--- a/backup/db/mysql.php
+++ b/backup/db/mysql.php
@@ -140,8 +140,8 @@ function backup_upgrade($oldversion=0) {
     if ($oldversion < 2006042100) {
         $result = execute_sql("ALTER TABLE {$CFG->prefix}backup_files DROP INDEX {$CFG->prefix}backup_files_uk");
         $result = execute_sql("ALTER TABLE {$CFG->prefix}backup_ids DROP INDEX {$CFG->prefix}backup_ids_uk");
-        $result = execute_sql("ALTER TABLE {$CFG->prefix}backup_files ADD UNIQUE INDEX {$CFG->prefix}backup_files_uk(backup_code,file_type(10),path(255))");
-        $result = execute_sql("ALTER TABLE {$CFG->prefix}backup_ids ADD UNIQUE INDEX {$CFG->prefix}backup_ids_uk(backup_code,table_name(30),old_id)");
+        $result = execute_sql("ALTER TABLE {$CFG->prefix}backup_files ADD UNIQUE INDEX backup_files_uk(backup_code,file_type(10),path(255))");
+        $result = execute_sql("ALTER TABLE {$CFG->prefix}backup_ids ADD UNIQUE INDEX backup_ids_uk(backup_code,table_name(30),old_id)");
     }