diff --git a/History.md b/History.md
index 9f211eb..7f96219 100644
--- a/History.md
+++ b/History.md
@@ -6,6 +6,7 @@
  * add req.host=
  * add: context.throw supports Error instances
  * update co
+ * update cookies
 
 0.2.1 / 2013-12-30
 ==================
diff --git a/lib/application.js b/lib/application.js
index 40790a2..4166b94 100644
--- a/lib/application.js
+++ b/lib/application.js
@@ -10,7 +10,6 @@ var context = require('./context');
 var request = require('./request');
 var response = require('./response');
 var Cookies = require('cookies');
-var Keygrip = require('keygrip');
 var accepts = require('accepts');
 var assert = require('assert');
 var http = require('http');
@@ -121,10 +120,10 @@ app.callback = function(){
  */
 
 app.__defineSetter__('keys', function(keys){
-  var ok = Array.isArray(keys) || keys instanceof Keygrip;
+  var ok = keys && (Array.isArray(keys)
+    || (keys.constructor && keys.constructor.name === 'Keygrip'));
   debug('keys %j', keys);
   if (!ok) throw new TypeError('app.keys must be an array or Keygrip');
-  if (!(keys instanceof Keygrip)) keys = new Keygrip(keys);
   this._keys = keys;
 });
 
diff --git a/package.json b/package.json
index dc970fc..bc466ab 100644
--- a/package.json
+++ b/package.json
@@ -29,8 +29,7 @@
     "mime": "~1.2.11",
     "fresh": "~0.2.1",
     "koa-compose": "~2.2.0",
-    "cookies": "~0.3.7",
-    "keygrip": "~1.0.0",
+    "cookies": "~0.4.0",
     "delegates": "0.0.3"
   },
   "devDependencies": {