diff --git a/lib/ace/lib/event.js b/lib/ace/lib/event.js
index bd63c66b..89d2756a 100644
--- a/lib/ace/lib/event.js
+++ b/lib/ace/lib/event.js
@@ -41,7 +41,7 @@ exports.addListener = function(elem, type, callback) {
     }
     if (elem.attachEvent) {
         var wrapper = function() {
-            callback(window.event);
+            callback.call(elem, window.event);
         };
         callback._wrapper = wrapper;
         elem.attachEvent("on" + type, wrapper);