diff --git a/packages/router/src/events.ts b/packages/router/src/events.ts
index 0cf8dc6415..2dd1ca6fba 100644
--- a/packages/router/src/events.ts
+++ b/packages/router/src/events.ts
@@ -30,8 +30,8 @@ export type NavigationTrigger = 'imperative'|'popstate'|'hashchange';
  * class MyService {
  *   constructor(public router: Router, logger: Logger) {
  *     router.events.pipe(
- *       filter(e => e instanceof RouterEvent)
- *     ).subscribe(e => {
+ *        filter((e: Event): e is RouterEvent => e instanceof RouterEvent)
+ *     ).subscribe((e: RouterEvent) => {
  *       logger.log(e.id, e.url);
  *     });
  *   }