diff --git a/phpgwapi/inc/class.translation.inc.php b/phpgwapi/inc/class.translation.inc.php
index 1d89f9a312..f31637a559 100644
--- a/phpgwapi/inc/class.translation.inc.php
+++ b/phpgwapi/inc/class.translation.inc.php
@@ -669,7 +669,8 @@ class translation
 		if ($upgrademethod == 'dumpold')
 		{
 			// dont delete the custom main- & loginscreen messages every time
-			self::$db->delete(self::LANG_TABLE,"app_name!='mainscreen' AND app_name!='loginscreen'",__LINE__,__FILE__);
+			self::$db->delete(self::LANG_TABLE,self::$db->expression(self::LANG_TABLE,
+				'NOT ',array('app_name'=>self::$instance_specific_translations)),__LINE__,__FILE__);
 			//echo '<br>Test: dumpold';
 			$GLOBALS['egw_info']['server']['lang_ctimes'] = array();
 		}