diff --git a/src/decorators.js b/src/decorators.js
index e8077330..160dc9ff 100644
--- a/src/decorators.js
+++ b/src/decorators.js
@@ -57,7 +57,7 @@ export function templateController(target){
 
 Decorators.configure.simpleDecorator('templateController', templateController);
 
-export function bindable(nameOrConfigOrTarget, key, descriptor){
+export function bindable(nameOrConfigOrTarget?, key?, descriptor?){
   var deco = function(target, key, descriptor){
     var actualTarget = key ? target.constructor : target, //is it on a property or a class?
         resource = Metadata.getOrCreateOwn(Metadata.resource, HtmlBehaviorResource, actualTarget),