diff --git a/lib/map.js b/lib/map.js
index 6f45e56..9502ad6 100644
--- a/lib/map.js
+++ b/lib/map.js
@@ -106,7 +106,8 @@ define(['map/clientlayer', 'map/labellayer', 'map/button', 'leaflet'],
       });
 
       map.on('load', function () {
-        document.querySelectorAll('.leaflet-control-layers-selector').forEach(function (input) {
+        var inputs = document.querySelectorAll('.leaflet-control-layers-selector');
+        [].forEach.call(inputs, function (input) {
           input.setAttribute('role', 'radiogroup');
           input.setAttribute('aria-label', input.nextSibling.innerHTML.trim());
         });