diff --git a/lib/serviceworkers.js b/lib/serviceworkers.js
index 645b1c6db7d..24221aab94f 100644
--- a/lib/serviceworkers.js
+++ b/lib/serviceworkers.js
@@ -132,6 +132,11 @@ declare class PushManager {
 
 type ServiceWorkerUpdateViaCache = 'imports' | 'all' | 'none';
 
+type GetNotificationOptions = {
+  tag?: string,
+  ...
+};
+
 declare class ServiceWorkerRegistration extends EventTarget {
   +installing: ?ServiceWorker,
   +waiting: ?ServiceWorker,
@@ -141,6 +146,8 @@ declare class ServiceWorkerRegistration extends EventTarget {
   +updateViaCache: ServiceWorkerUpdateViaCache,
   +pushManager: PushManager,
 
+  getNotifications?: (filter?: GetNotificationOptions) => Promise<$ReadOnlyArray<Notification>>,
+  showNotification?: (title: string, options?: NotificationOptions) => Promise<void>,
   update(): Promise<void>,
   unregister(): Promise<boolean>,