diff --git a/common/bootstrap.js b/common/bootstrap.js
index 636fa686..795e9fe5 100755
--- a/common/bootstrap.js
+++ b/common/bootstrap.js
@@ -113,7 +113,7 @@ let JSMLoader = {
 
     atexit: function atexit(arg, self) {
         if (typeof arg !== "string")
-            this._atexit.push(arguments);
+            this._atexit.push([arg, self]);
         else
             for (let [fn, self] of this._atexit)
                 try {
diff --git a/common/modules/main.jsm b/common/modules/main.jsm
index 73b1b624..cbfafec2 100644
--- a/common/modules/main.jsm
+++ b/common/modules/main.jsm
@@ -125,8 +125,16 @@ var Modules = function Modules(window) {
             return p;
         },
 
-        set: function window_set(target, prop, val) {
-            return target[prop] = val;
+        set: function window_set(target, prop, val, receiver) {
+            if (receiver !== target)
+                Object.defineProperty(receiver, prop, {
+                    value: val,
+                    enumerable: true, configurable: true, writable: true
+                });
+            else
+                target[prop] = val;
+
+            return true;
         }
     });
 
@@ -249,7 +257,9 @@ overlay.overlayWindow(Object.keys(config.overlays),
     cleanup: function cleanup(window) {
         overlay.windows.delete(window);
 
-        Cu.nukeSandbox(this.jsmodules);
+        JSMLoader.atexit(() => {
+            Cu.nukeSandbox(this.jsmodules);
+        });
     },
 
     unload: function unload(window) {
diff --git a/common/modules/overlay.jsm b/common/modules/overlay.jsm
index cb054ced..86a59661 100644
--- a/common/modules/overlay.jsm
+++ b/common/modules/overlay.jsm
@@ -102,7 +102,7 @@ var Overlay = Module("Overlay", XPCOM([Ci.nsIObserver, Ci.nsISupportsWeakReferen
         if (event === true)
             target = null;
 
-        this.setData(doc, "listeners", listeners.filter(function (args) {
+        this.setData(doc, "listeners", listeners.filter(args => {
             let elem = args[0].get();
             if (target == null || elem == target && args[1] == event && args[2].wrapped == callback && args[3] == capture) {
                 apply(elem, "removeEventListener", args.slice(1));