diff --git a/History.md b/History.md
index 6e312ee..3de7366 100644
--- a/History.md
+++ b/History.md
@@ -1,3 +1,7 @@
+HEAD
+==================
+
+ * update co
 
 0.1.1 / 2013-12-19
 ==================
diff --git a/lib/application.js b/lib/application.js
index 7ef2762..9036c82 100644
--- a/lib/application.js
+++ b/lib/application.js
@@ -94,13 +94,14 @@ app.use = function(fn){
 app.callback = function(){
   var mw = [respond].concat(this.middleware);
   var gen = compose(mw);
+  var fn = co(gen);
   var self = this;
 
   return function(req, res, next){
     var ctx = self.createContext(req, res);
     next = next || ctx.onerror;
     ctx.onSocketError(next);
-    co.call(ctx, gen)(next);
+    fn.call(ctx, next);
   }
 };
 
diff --git a/package.json b/package.json
index 4f4282b..2c1f00b 100644
--- a/package.json
+++ b/package.json
@@ -21,7 +21,7 @@
   ],
   "license": "MIT",
   "dependencies": {
-    "co": "~2.3.0",
+    "co": "~3.0.0",
     "debug": "*",
     "mime": "~1.2.11",
     "fresh": "~0.2.0",