diff --git a/at_core/scripts/menu-toggle.js b/at_core/scripts/menu-toggle.js
index 7bd1457..416954d 100755
--- a/at_core/scripts/menu-toggle.js
+++ b/at_core/scripts/menu-toggle.js
@@ -7,6 +7,9 @@
 
       var activeTheme = Drupal.settings["ajaxPageState"]["theme"];
       var themeSettings = Drupal.settings['adaptivetheme'];
+      if (typeof themeSettings[activeTheme] == 'undefined') {
+        return;
+      }
       var mtsTP = themeSettings[activeTheme]['menu_toggle_settings']['tablet_portrait'];
       var mtsTL = themeSettings[activeTheme]['menu_toggle_settings']['tablet_landscape'];