diff --git a/backup/restore.php b/backup/restore.php
index 6999d707e25..9c5eb63a701 100644
--- a/backup/restore.php
+++ b/backup/restore.php
@@ -14,6 +14,7 @@
     //Units used
     require_once ("$moodle_home/config.php");
     require_once ("$moodle_home/version.php");
+    require_once ("$moodle_home/lib/xmlize.php");
     require_once ("backup_version.php");
     require_once ("db/backup_$CFG->dbtype.php");
     require_once ("lib.php");