Cannot resolve toPromise in an angular webservice

I am trying to create a very simple angular service:

import { Http, Response } from '@angular/http';
import 'rxjs/add/operator/toPromise';

export class Webservice {

  constructor(private http: Http) {

  }

  getMessages() {
    return this.http.get('http://localhost:63962/api/someshittyendpoint').toPromise();
  }
}

Whatever I do, I get the following Module not found: Error: Can't resolve 'rxjs/add/operator/toPromise'.

I have installed rxjs-compat and verified that the module actually is on the path. I don't understand what's wrong?

Thanks in advance!