diff --git a/phpgwapi/inc/class.db_backup.inc.php b/phpgwapi/inc/class.db_backup.inc.php
index e5f8609bf6..64ac0a5b3e 100644
--- a/phpgwapi/inc/class.db_backup.inc.php
+++ b/phpgwapi/inc/class.db_backup.inc.php
@@ -623,6 +623,9 @@ class db_backup
 		// search-and-register-hooks
 		$GLOBALS['egw']->hooks->register_all_hooks();
 
+		// invalidate categories cache, it's instance wide
+		categories::invalidate_cache();
+
 		return '';
 	}