diff --git a/spec/observables/forkJoin-spec.ts b/spec/observables/forkJoin-spec.ts
index 06f9f2a92e..b6b5203785 100644
--- a/spec/observables/forkJoin-spec.ts
+++ b/spec/observables/forkJoin-spec.ts
@@ -1,7 +1,12 @@
 import {expect} from 'chai';
 import * as Rx from '../../dist/cjs/Rx';
-declare const {hot, expectObservable, expectSubscriptions, type};
 import {lowerCaseO} from '../helpers/test-helper';
+import marbleTestingSignature = require('../helpers/marble-testing'); // tslint:disable-line:no-require-imports
+
+declare const {type};
+declare const hot: typeof marbleTestingSignature.hot;
+declare const expectObservable: typeof marbleTestingSignature.expectObservable;
+declare const expectSubscriptions: typeof marbleTestingSignature.expectSubscriptions;
 
 const Observable = Rx.Observable;
 
diff --git a/src/observable/ForkJoinObservable.ts b/src/observable/ForkJoinObservable.ts
index 062dc6e6d1..6fa17aef3b 100644
--- a/src/observable/ForkJoinObservable.ts
+++ b/src/observable/ForkJoinObservable.ts
@@ -25,6 +25,7 @@ export class ForkJoinObservable<T> extends Observable<T> {
   static create<T, T2, T3, T4>(v1: SubscribableOrPromise<T>, v2: SubscribableOrPromise<T2>, v3: SubscribableOrPromise<T3>, v4: SubscribableOrPromise<T4>): Observable<[T, T2, T3, T4]>;
   static create<T, T2, T3, T4, T5>(v1: SubscribableOrPromise<T>, v2: SubscribableOrPromise<T2>, v3: SubscribableOrPromise<T3>, v4: SubscribableOrPromise<T4>, v5: SubscribableOrPromise<T5>): Observable<[T, T2, T3, T4, T5]>;
   static create<T, T2, T3, T4, T5, T6>(v1: SubscribableOrPromise<T>, v2: SubscribableOrPromise<T2>, v3: SubscribableOrPromise<T3>, v4: SubscribableOrPromise<T4>, v5: SubscribableOrPromise<T5>, v6: SubscribableOrPromise<T6>): Observable<[T, T2, T3, T4, T5, T6]>;
+  static create<T, R>(v1: SubscribableOrPromise<T>, project: (v1: T) => R): Observable<R>;
   static create<T, T2, R>(v1: SubscribableOrPromise<T>, v2: SubscribableOrPromise<T2>, project: (v1: T, v2: T2) => R): Observable<R>;
   static create<T, T2, T3, R>(v1: SubscribableOrPromise<T>, v2: SubscribableOrPromise<T2>, v3: SubscribableOrPromise<T3>, project: (v1: T, v2: T2, v3: T3) => R): Observable<R>;
   static create<T, T2, T3, T4, R>(v1: SubscribableOrPromise<T>, v2: SubscribableOrPromise<T2>, v3: SubscribableOrPromise<T3>, v4: SubscribableOrPromise<T4>, project: (v1: T, v2: T2, v3: T3, v4: T4) => R): Observable<R>;