diff --git a/types/kefir/index.d.ts b/types/kefir/index.d.ts
index f1209b312a..ff93bf4cb7 100644
--- a/types/kefir/index.d.ts
+++ b/types/kefir/index.d.ts
@@ -119,7 +119,7 @@ export class Observable<T, S> {
     sampledBy(otherObs: Observable<any, any>): Observable<T, S>;
     sampledBy<U, W>(otherObs: Observable<U, any>, combinator: (a: T, b: U) => W): Observable<W, S>;
     skipUntilBy<U, V>(otherObs: Observable<U, V>): Observable<U, V>;
-    takeUntilBy<U, V>(otherObs: Observable<U, V>): Observable<U, V>;
+    takeUntilBy<U, V>(otherObs: Observable<U, V>): Observable<T, S>;
     bufferBy<U, V>(otherObs: Observable<U, V>, options?: { flushOnEnd: boolean }): Observable<T[], S>;
     bufferWhileBy<U>(otherObs: Observable<boolean, U>, options?: { flushOnEnd?: boolean, flushOnChange?: boolean }): Observable<T[], S>;
     awaiting<U, V>(otherObs: Observable<U, V>): Observable<boolean, S>;
diff --git a/types/kefir/kefir-tests.ts b/types/kefir/kefir-tests.ts
index f93da894e1..28f37b915e 100644
--- a/types/kefir/kefir-tests.ts
+++ b/types/kefir/kefir-tests.ts
@@ -219,8 +219,8 @@ import { Observable, Pool, Stream, Property, Event, Emitter } from 'kefir';
 	}
 	{
 		let foo: Stream<number, void>  = Kefir.sequentially(100, [1, 2, 3, 4]);
-		let bar: Stream<number, void>  = Kefir.later(250, 0);
-		let observable04: Stream<number, void> = foo.takeUntilBy<number, void>(bar);
+		let bar: Stream<string, void>  = Kefir.later(250, 'hello');
+		let observable04: Stream<number, void> = foo.takeUntilBy<string, void>(bar);
 	}
 	{
 		let foo: Stream<number, void>  = Kefir.sequentially(100, [1, 2, 3, 4, 5, 6, 7, 8]).delay(40);