diff --git a/lib/ace/lib/event_emitter.js b/lib/ace/lib/event_emitter.js
index 482ae0d4..b9860145 100644
--- a/lib/ace/lib/event_emitter.js
+++ b/lib/ace/lib/event_emitter.js
@@ -55,6 +55,7 @@ EventEmitter._dispatchEvent = function(eventName, e) {
     if (!e.preventDefault)
         e.preventDefault = preventDefault;
 
+    listeners = listeners.slice();
     for (var i=0; i<listeners.length; i++) {
         listeners[i](e, this);
         if (e.propagationStopped)
@@ -70,7 +71,7 @@ EventEmitter._signal = function(eventName, e) {
     var listeners = (this._eventRegistry || {})[eventName];
     if (!listeners)
         return;
-
+    listeners = listeners.slice();
     for (var i=0; i<listeners.length; i++)
         listeners[i](e, this);
 };