diff --git a/kew.js b/kew.js
index 7172546..978889c 100644
--- a/kew.js
+++ b/kew.js
@@ -1,16 +1,13 @@
-/** @typedef {function(?, ?)} */
-var OnSuccessCallbackType;
-/** @typedef {function(!Error, ?)} */
-var OnFailCallbackType;
 
 /**
  * An object representing a "promise" for a future value
  *
- * @param {?OnSuccessCallbackType=} onSuccess a function to handle successful
+ * @param {?function(T)=} onSuccess a function to handle successful
  *     resolution of this promise
- * @param {OnFailCallbackType=} onFail a function to handle failed
+ * @param {?function(!Error)=} onFail a function to handle failed
  *     resolution of this promise
  * @constructor
+ * @template T
  */
 function Promise(onSuccess, onFail) {
   this.promise = this
@@ -148,8 +145,8 @@ Promise.prototype.reject = function (e) {
  * resolves. Allows for an optional second callback to handle the failure
  * case.
  *
- * @param {?OnSuccessCallbackType} onSuccess
- * @param {OnFailCallbackType=} onFail
+ * @param {?function(this:void, T)} onSuccess
+ * @param {?function(this:void, !Error)=} onFail
  * @return {!Promise} returns a new promise with the output of the onSuccess or
  *     onFail handler
  */
@@ -167,10 +164,11 @@ Promise.prototype.then = function (onSuccess, onFail) {
  * Provide a callback to be called whenever this promise successfully
  * resolves. The callback will be executed in the context of the provided scope.
  *
- * @param {?OnSuccessCallbackType} onSuccess
- * @param {Object} scope Object whose context callback will be executed in.
+ * @param {function(this:SCOPE, T)} onSuccess
+ * @param {SCOPE} scope Object whose context callback will be executed in.
  * @param {...*} var_args Additional arguments to be passed to the promise callback.
  * @return {!Promise} returns a new promise with the output of the onSuccess
+ * @template SCOPE
  */
 Promise.prototype.thenBound = function (onSuccess, scope, var_args) {
   var promise = new Promise(onSuccess)
@@ -191,7 +189,7 @@ Promise.prototype.thenBound = function (onSuccess, scope, var_args) {
 /**
  * Provide a callback to be called whenever this promise is rejected
  *
- * @param {OnFailCallbackType} onFail
+ * @param {function(this:void, !Error)} onFail
  * @return {!Promise} returns a new promise with the output of the onFail handler
  */
 Promise.prototype.fail = function (onFail) {
@@ -202,11 +200,13 @@ Promise.prototype.fail = function (onFail) {
  * Provide a callback to be called whenever this promise is rejected.
  * The callback will be executed in the context of the provided scope.
  *
- * @param {OnFailCallbackType} onFail
- * @param {Object} scope Object whose context callback will be executed in.
+ * @param {function(this:SCOPE, Error)} onFail
+ * @param {SCOPE} scope Object whose context callback will be executed in.
+ * @param {...?} var_args
  * @return {!Promise} returns a new promise with the output of the onSuccess
+ * @template SCOPE
  */
-Promise.prototype.failBound = function (onFail, scope) {
+Promise.prototype.failBound = function (onFail, scope, var_args) {
   var promise = new Promise(null, onFail)
   if (this._nextContext) promise._useContext(this._nextContext)
 
diff --git a/package.json b/package.json
index fc9375d..fd87902 100644
--- a/package.json
+++ b/package.json
@@ -22,7 +22,7 @@
   "devDependencies": {
     "q": "0.9.7",
     "nodeunit": "0.8.1",
-    "closure-npc": "0.0.9"
+    "closure-npc": "0.0.10"
   },
   "scripts": {
     "test": "nodeunit test && closure-npc ./test/closure_test.js --jscomp_error=checkTypes"