--- gnome-shell-3.17.3/js/ui/windowManager.js~	2015-07-02 13:55:34.000000000 +0200
+++ gnome-shell-3.17.3/js/ui/windowManager.js	2015-07-03 22:23:11.287013783 +0200
@@ -217,7 +217,7 @@
 
     _getWorkspaceSettings: function() {
         let settings = global.get_overrides_settings();
-        if (settings.settings_schema.list_keys().indexOf('dynamic-workspaces') > -1)
+        if (settings.settings_schema.list_keys && settings.settings_schema.list_keys().indexOf('dynamic-workspaces') > -1)
             return settings;
         return new Gio.Settings({ schema_id: 'org.gnome.mutter' });
     },
