diff --git a/.jshintrc b/.jshintrc
index 7427dce48..c66d74c88 100644
--- a/.jshintrc
+++ b/.jshintrc
@@ -20,6 +20,7 @@
     "browser": true,
     "node": true,
     "globals": {
+        "self": true,
         "define": true
     }
 }
diff --git a/lib/async.js b/lib/async.js
index 59ff57b97..41d33cb4a 100644
--- a/lib/async.js
+++ b/lib/async.js
@@ -11,17 +11,14 @@
     function noop() {}
 
     // global on the server, window in the browser
-    var root, previous_async;
-
-    if (typeof window == 'object' && this === window) {
-        root = window;
-    }
-    else if (typeof global == 'object' && this === global) {
-        root = global;
-    }
-    else {
-        root = this;
-    }
+    var previous_async;
+
+    // Establish the root object, `window` (`self`) in the browser, `global`
+    // on the server, or `this` in some virtual machines. We use `self`
+    // instead of `window` for `WebWorker` support.
+    var root = typeof self === 'object' && self.self === self && self ||
+            typeof global === 'object' && global.global === global && global ||
+            this;
 
     if (root != null) {
         previous_async = root.async;