rxjs-websockets: Argument of type 'QueueingSubject<{}>' is not assignable to parameter of type 'Observable'

With rxjs-websockets 1.1.0, queueing-subject 0.1.1 & typescript 2.4.2 I have the following code:

import Rx from "rxjs/Rx";
import { QueueingSubject } from "queueing-subject";
import websocketConnect, {Connection} from "rxjs-websockets";

const queuingSubject = new QueueingSubject();

// ...

const connection: Connection =  websocketConnect(
    myUrl,
    queuingSubject,
    myWebSocket
);

After upgrading from rxjs 5.4.2 to 5.4.3 I get the following type error in the webSocketConnect call:

error TS2345: Argument of type 'QueueingSubject<{}>' is not assignable to parameter of type 'Observable<any>'.  
Property 'source' is protected but type 'Observable<T>' is not a class derived from 'Observable<T>'.

I cleaned the cache (I’m using yarn), deleted node_modules and reinstalled but still get this error…