diff --git a/src/chrome/content/overlay.js b/src/chrome/content/overlay.js
index 3367f21..e8319fe 100644
--- a/src/chrome/content/overlay.js
+++ b/src/chrome/content/overlay.js
@@ -74,30 +74,29 @@ var firetrayChrome = { // each new window gets a new firetrayChrome !
    * we override the fake buttons' default actions.
    */
   hijackTitlebarButtons: function() {
-    Object.keys(this.titlebarDispatch).map(function(val, idx) {
-      let fInfo = firetrayChrome.replaceCommand(val, firetrayChrome.titlebarDispatch[val]['new']);
+    this.titlebarDispatch.forEach(function(button) {
+      let fInfo = firetrayChrome.replaceCommand(button.id, button.new);
       if (fInfo) {
-        firetrayChrome.titlebarDispatch[val]['old'] = fInfo[0];
-        firetray_log.debug('replaced command='+val+' type='+fInfo[1]+' func='+fInfo[0]);
-        firetrayChrome.titlebarDispatch[val]['type'] = fInfo[1];
+        button.old = fInfo[0];
+        firetray_log.debug('replaced command='+button.id+' type='+fInfo[1]+' func='+fInfo[0]);
+        button.type = fInfo[1];
       }
     });
   },
 
-  titlebarDispatch: {
-    "titlebar-min": {new: function(e){
+  titlebarDispatch: [
+    {id: "titlebar-min", new: function(e){
       firetray_log.debug('  titlebar-min clicked');
       if (!firetray.Handler.onMinimize(firetrayChrome.winId))
         firetrayChrome.applyDefaultCommand("titlebar-min");
     }, old: null, type: null},
-
-    "titlebar-close": {new: function(e){
+    {id: "titlebar-close", new: function(e){
       firetray_log.debug('  titlebar-close clicked');
       if (!firetrayChrome.onClose(null)) {
         firetrayChrome.applyDefaultCommand("titlebar-close");
       }
     }, old: null, type: null}
-  },
+  ],
 
   replaceCommand: function(eltId, func) {
     let elt = document.getElementById(eltId);