diff --git a/admin/include/languages.class.php b/admin/include/languages.class.php
index d9537bbdd..3344c1e30 100644
--- a/admin/include/languages.class.php
+++ b/admin/include/languages.class.php
@@ -137,7 +137,7 @@ UPDATE '.USER_INFOS_TABLE.'
         $query = '
 UPDATE '.USER_INFOS_TABLE.'
   SET language = \''.$language_id.'\'
-  WHERE user_id = '.$conf['default_user_id'].'
+  WHERE user_id IN ('.$conf['default_user_id'].', '.$conf['guest_id'].')
 ;';
         pwg_query($query);
         break;