diff --git a/test/asset/set.js b/test/asset/set.js
index d32d124ed..7b888ed2d 100644
--- a/test/asset/set.js
+++ b/test/asset/set.js
@@ -9,17 +9,28 @@
   /** Used as the `Set#toString` return value. */
   var nativeString = String(Object.prototype.toString).replace(/toString/g, 'Set');
 
-  /** Used as a reference to the global object. */
-  var root = (objectTypes[typeof window] && window) || this;
-
   /** Detect free variable `exports`. */
   var freeExports = objectTypes[typeof exports] && exports && !exports.nodeType && exports;
 
-  /** Detect free variable `global` from Node.js or Browserified code and use it as `root`. */
-  var freeGlobal = objectTypes[typeof global] && global;
-  if (freeGlobal && (freeGlobal.global === freeGlobal || freeGlobal.window === freeGlobal || freeGlobal.self === freeGlobal)) {
-    root = freeGlobal;
-  }
+  /** Detect free variable `module`. */
+  var freeModule = objectTypes[typeof module] && module && !module.nodeType && module;
+
+  /** Detect free variable `global` from Node.js. */
+  var freeGlobal = freeExports && freeModule && typeof global == 'object' && global;
+
+  /** Detect free variable `self`. */
+  var freeSelf = objectTypes[typeof self] && self && self.Object && self;
+
+  /** Detect free variable `window`. */
+  var freeWindow = objectTypes[typeof window] && window && window.Object && window;
+
+  /**
+   * Used as a reference to the global object.
+   *
+   * The `this` value is used if it is the global object to avoid Greasemonkey's
+   * restricted `window` object, otherwise the `window` object is used.
+   */
+  var root = freeGlobal || ((freeWindow !== (this && this.window)) && freeWindow) || freeSelf || this;
 
   /*--------------------------------------------------------------------------*/
 
diff --git a/test/asset/weakmap.js b/test/asset/weakmap.js
index 7040876e6..17ef09120 100644
--- a/test/asset/weakmap.js
+++ b/test/asset/weakmap.js
@@ -9,17 +9,28 @@
   /** Used as the `WeakMap#toString` return value. */
   var nativeString = String(Object.prototype.toString).replace(/toString/g, 'WeakMap');
 
-  /** Used as a reference to the global object. */
-  var root = (objectTypes[typeof window] && window) || this;
-
   /** Detect free variable `exports`. */
   var freeExports = objectTypes[typeof exports] && exports && !exports.nodeType && exports;
 
-  /** Detect free variable `global` from Node.js or Browserified code and use it as `root`. */
-  var freeGlobal = objectTypes[typeof global] && global;
-  if (freeGlobal && (freeGlobal.global === freeGlobal || freeGlobal.window === freeGlobal || freeGlobal.self === freeGlobal)) {
-    root = freeGlobal;
-  }
+  /** Detect free variable `module`. */
+  var freeModule = objectTypes[typeof module] && module && !module.nodeType && module;
+
+  /** Detect free variable `global` from Node.js. */
+  var freeGlobal = freeExports && freeModule && typeof global == 'object' && global;
+
+  /** Detect free variable `self`. */
+  var freeSelf = objectTypes[typeof self] && self && self.Object && self;
+
+  /** Detect free variable `window`. */
+  var freeWindow = objectTypes[typeof window] && window && window.Object && window;
+
+  /**
+   * Used as a reference to the global object.
+   *
+   * The `this` value is used if it is the global object to avoid Greasemonkey's
+   * restricted `window` object, otherwise the `window` object is used.
+   */
+  var root = freeGlobal || ((freeWindow !== (this && this.window)) && freeWindow) || freeSelf || this;
 
   /*--------------------------------------------------------------------------*/