diff --git a/lib/clientsidescripts.js b/lib/clientsidescripts.js
index dd99ebe20..e86f776fa 100644
--- a/lib/clientsidescripts.js
+++ b/lib/clientsidescripts.js
@@ -137,7 +137,7 @@ functions.waitForAngular = function(rootSelector, callback) {
     if (window.angular && !(window.angular.version &&
           window.angular.version.major > 1)) {
       /* ng1 */
-      let hooks = getNg1Hooks(rootSelector);
+      var hooks = getNg1Hooks(rootSelector);
       if (hooks.$$testability) {
         hooks.$$testability.whenStable(callback);
       } else if (hooks.$injector) {