diff --git a/src/operator/concatAll.ts b/src/operator/concatAll.ts
index e81ed990f7..5b5920b492 100644
--- a/src/operator/concatAll.ts
+++ b/src/operator/concatAll.ts
@@ -1,10 +1,9 @@
-import { Observable } from '../Observable';
-import { Subscribable } from '../Observable';
+import { Observable, ObservableInput } from '../Observable';
 import { MergeAllOperator } from './mergeAll';
 
 /* tslint:disable:max-line-length */
-export function concatAll<T>(this: Observable<T>): T;
-export function concatAll<T, R>(this: Observable<T>): Subscribable<R>;
+export function concatAll<T>(this: Observable<T[]>): Observable<T>;
+export function concatAll<T extends ObservableInput<R>, R>(this: Observable<T>): Observable<R>;
 /* tslint:enable:max-line-length */
 
 /**
diff --git a/src/operator/mergeAll.ts b/src/operator/mergeAll.ts
index 73fed64cfd..f50dfbbc8a 100644
--- a/src/operator/mergeAll.ts
+++ b/src/operator/mergeAll.ts
@@ -1,13 +1,12 @@
-import { Observable } from '../Observable';
+import { Observable, ObservableInput } from '../Observable';
 import { Operator } from '../Operator';
 import { Observer } from '../Observer';
 import { Subscription } from '../Subscription';
 import { OuterSubscriber } from '../OuterSubscriber';
-import { Subscribable } from '../Observable';
 import { subscribeToResult } from '../util/subscribeToResult';
 
-export function mergeAll<T>(this: Observable<T>, concurrent?: number): T;
-export function mergeAll<T, R>(this: Observable<T>, concurrent?: number): Subscribable<R>;
+export function mergeAll<T>(this: Observable<T[]>, concurrent?: number): Observable<T>;
+export function mergeAll<T extends ObservableInput<R>, R>(this: Observable<T>, concurrent?: number): Observable<R>;
 
 /**
  * Converts a higher-order Observable into a first-order Observable which