diff --git a/src/Subject.ts b/src/Subject.ts
index 4bc9b66650f..89e681da8e5 100644
--- a/src/Subject.ts
+++ b/src/Subject.ts
@@ -29,10 +29,10 @@ export class Subject<T> extends Observable<T> implements Observer<T>, Subscripti
   protected dispatching: boolean = false;
   protected hasCompleted: boolean = false;
 
-  lift<R>(operator: Operator<T, R>): Observable<T> {
-    const subject = new Subject(this, this.destination || this);
+  lift<R>(operator: Operator<T, R>): Observable<R> {
+    const subject = new Subject<R>(this, this.destination || this);
     subject.operator = operator;
-    return <any>subject;
+    return subject;
   }
 
   add(subscription: Subscription|Function|void): void {