diff --git a/common/modules/main.jsm b/common/modules/main.jsm
index bc0a2da6..80e64a79 100644
--- a/common/modules/main.jsm
+++ b/common/modules/main.jsm
@@ -110,34 +110,49 @@ var Modules = function Modules(window) {
 
     const BASES = [BASE, "resource://dactyl-local-content/"];
 
-    var traps = {
-        get: function window_get(target, prop) {
-            // `in`, not `hasOwnProperty`, because we want to return
-            // unbound methods in `Object.prototype`
-            if (prop in proxyCache)
-                return proxyCache[prop];
-
-            let p = target[prop];
-            if (callable(p))
-                return proxyCache[prop] = p.bind(target);
-
-            return p;
-        },
-
-        set: function window_set(target, prop, val) {
-            return target[prop] = val;
-        }
-    };
-
     let proxyCache = {};
     if (config.haveGecko(29))
-        var proxy = new Proxy(window, traps);
+        var proxy = new Proxy(window, {
+            get: function window_get(target, prop) {
+                // `in`, not `hasOwnProperty`, because we want to return
+                // unbound methods in `Object.prototype`
+                if (prop in proxyCache)
+                    return proxyCache[prop];
+
+                let p = target[prop];
+                if (callable(p))
+                    return proxyCache[prop] = p.bind(target);
+
+                return p;
+            },
+
+            set: function window_set(target, prop, val) {
+                return target[prop] = val;
+            }
+        });
     else {
         // Bug 814892
         let o = {};
         // Oh, the brokenness... See bug 793210
         Object.preventExtensions(o);
-        proxy = new Proxy(o, update(traps, {
+        proxy = new Proxy(o, {
+            get: function window_get(target, prop) {
+                // `in`, not `hasOwnProperty`, because we want to return
+                // unbound methods in `Object.prototype`
+                if (prop in proxyCache)
+                    return proxyCache[prop];
+
+                let p = window[prop];
+                if (callable(p))
+                    return proxyCache[prop] = p.bind(window);
+
+                return p;
+            },
+
+            set: function window_set(target, prop, val) {
+                return window[prop] = val;
+            },
+
             getOwnPropertyDescriptor: function (target, prop) Object.getOwnPropertyDescriptor(window, prop),
             getOwnPropertyNames: function (target, prop) Object.getOwnPropertyNames(window),
             defineProperty: function (target, prop, desc) Object.defineProperty(window, prop, desc),
@@ -146,7 +161,7 @@ var Modules = function Modules(window) {
             hasOwn: function (target, prop) hasOwnProperty(window, prop),
             enumerate: function (target) (p for (p in window)),
             iterate: function (target) (p for (p of window))
-        }));
+        });
     }
 
     var jsmodules = newContext(proxy, false, "Dactyl `jsmodules`");