diff --git a/rx/rx-lite.d.ts b/rx/rx-lite.d.ts
index c7a148137..eea3c55ce 100644
--- a/rx/rx-lite.d.ts
+++ b/rx/rx-lite.d.ts
@@ -49,6 +49,8 @@ declare module Rx {
 
 	export module helpers {
 		function noop(): void;
+		function notDefined(value: any): boolean;
+		function isScheduler(value: any): boolean;
 		function identity<T>(value: T): T;
 		function defaultNow(): number;
 		function defaultComparer(left: any, right: any): boolean;