diff --git a/source/Ox/js/Function.js b/source/Ox/js/Function.js
index d023f0ea..93f98821 100644
--- a/source/Ox/js/Function.js
+++ b/source/Ox/js/Function.js
@@ -17,10 +17,9 @@ Ox.cache <f> Memoize a function
 // TODO: add async test
 Ox.cache = function(fn, options) {
     var cache = {}, ret;
-    options = Ox.extend({
-        async: false,
-        key: JSON.stringify
-    }, options || {});
+    options = options || {};
+    options.async = options.async || false;
+    options.key = options.key || JSON.stringify;
     ret = function() {
         var args = Ox.slice(arguments), key = options.key(args);
         function callback() {