diff --git a/dom/push/test/test_unregister.html b/dom/push/test/test_unregister.html
index 6ce0b18cb2f6..c528f32e92ea 100644
--- a/dom/push/test/test_unregister.html
+++ b/dom/push/test/test_unregister.html
@@ -10,6 +10,7 @@ http://creativecommons.org/licenses/publicdomain/
 <head>
   <title>Test for Bug 1170817</title>
   <script type="text/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="/tests/SimpleTest/SpawnTask.js"></script>
   <script type="text/javascript" src="/tests/dom/push/test/test_utils.js"></script>
   <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
   <meta http-equiv="Content-type" content="text/html;charset=UTF-8">
@@ -24,65 +25,54 @@ http://creativecommons.org/licenses/publicdomain/
 
 <script class="testbody" type="text/javascript">
 
+  function generateURL() {
+    return "worker.js" + "?" + (Math.random());
+  }
+
   var registration;
+  add_task(function* start() {
+    yield setupPrefsAndMockSocket(new MockWebSocket());
+    yield setPushPermission(true);
 
-  function start() {
-    return navigator.serviceWorker.register("worker.js" + "?" + (Math.random()), {scope: "."})
-    .then(swr => { registration = swr; return swr; });
-  }
+    registration = yield navigator.serviceWorker.register(
+      generateURL(), {scope: "."});
+  });
 
-  function unregisterSW() {
-    return registration.unregister().then(function(result) {
-      ok(result, "Unregister should return true.");
-    }, function(e) {
-      dump("Unregistering the SW failed with " + e + "\n");
-    });
-  }
+  var pushSubscription;
+  add_task(function* setupPushNotification() {
+    pushSubscription = yield registration.pushManager.subscribe();
+    ok(pushSubscription, "successful registered for push notification");
+  });
 
-  function setupPushNotification(swr) {
-    return swr.pushManager.subscribe().then(
-      pushSubscription => {
-        ok(true, "successful registered for push notification");
-        return pushSubscription;
-      }, error => {
-        ok(false, "could not register for push notification");
-      });
-  }
+  add_task(function* unregisterPushNotification() {
+    var result = yield pushSubscription.unsubscribe();
+    ok(result, "unsubscribe() on existing subscription should return true.");
+  });
 
-  function unregisterPushNotification(pushSubscription) {
-    return pushSubscription.unsubscribe().then(
-      result => {
-      ok(result, "unsubscribe() on existing subscription should return true.");
-      return pushSubscription;
-    }, error => {
-      ok(false, "unsubscribe() should never fail.");
-    });
-  }
+  add_task(function* unregisterAgain() {
+    var result = yield pushSubscription.unsubscribe();
+    ok(!result, "unsubscribe() on previously unsubscribed subscription should return false.");
+  });
 
-  function unregisterAgain(pushSubscription) {
-    return pushSubscription.unsubscribe().then(
-      result => {
-      ok(!result, "unsubscribe() on previously unsubscribed subscription should return false.");
-      return pushSubscription;
-    }, error => {
-      ok(false, "unsubscribe() should never fail.");
-    });
-  }
+  add_task(function* subscribeAgain() {
+    pushSubscription = yield registration.pushManager.subscribe();
+    ok(pushSubscription, "Should create a new push subscription");
 
-  function runTest() {
-    start()
-    .then(setupPushNotification)
-    .then(unregisterPushNotification)
-    .then(unregisterAgain)
-    .then(unregisterSW)
-    .catch(function(e) {
-      ok(false, "Some test failed with error " + e);
-    }).then(SimpleTest.finish);
-  }
+    var result = yield registration.unregister();
+    ok(result, "Should unregister the service worker");
+
+    registration = yield navigator.serviceWorker.register(
+      generateURL(), {scope: "."});
+    var pushSubscription = yield registration.pushManager.getSubscription();
+    ok(!pushSubscription,
+      "Unregistering a service worker should drop its subscription");
+  });
+
+  add_task(function* unregister() {
+    var result = yield registration.unregister();
+    ok(result, "Unregister should return true.");
+  });
 
-  setupPrefsAndMockSocket(new MockWebSocket()).then(_ => runTest());
-  SpecialPowers.addPermission("desktop-notification", true, document);
-  SimpleTest.waitForExplicitFinish();
 </script>
 </body>
 </html>
diff --git a/dom/workers/ServiceWorkerUnregisterJob.cpp b/dom/workers/ServiceWorkerUnregisterJob.cpp
index 839e4250ca38..98b47d7dac0e 100644
--- a/dom/workers/ServiceWorkerUnregisterJob.cpp
+++ b/dom/workers/ServiceWorkerUnregisterJob.cpp
@@ -6,10 +6,44 @@
 
 #include "ServiceWorkerUnregisterJob.h"
 
+#include "nsIPushService.h"
+
 namespace mozilla {
 namespace dom {
 namespace workers {
 
+class ServiceWorkerUnregisterJob::PushUnsubscribeCallback final :
+        public nsIUnsubscribeResultCallback
+{
+public:
+  NS_DECL_ISUPPORTS
+
+  explicit PushUnsubscribeCallback(ServiceWorkerUnregisterJob* aJob)
+    : mJob(aJob)
+  {
+    AssertIsOnMainThread();
+  }
+
+  NS_IMETHODIMP
+  OnUnsubscribe(nsresult aStatus, bool) override
+  {
+    // Warn if unsubscribing fails, but don't prevent the worker from
+    // unregistering.
+    Unused << NS_WARN_IF(NS_FAILED(aStatus));
+    mJob->Unregister();
+    return NS_OK;
+  }
+
+private:
+  ~PushUnsubscribeCallback()
+  {
+  }
+
+  RefPtr<ServiceWorkerUnregisterJob> mJob;
+};
+
+NS_IMPL_ISUPPORTS(ServiceWorkerUnregisterJob::PushUnsubscribeCallback,
+                  nsIUnsubscribeResultCallback)
 
 ServiceWorkerUnregisterJob::ServiceWorkerUnregisterJob(nsIPrincipal* aPrincipal,
                                                        const nsACString& aScope,
@@ -41,6 +75,35 @@ ServiceWorkerUnregisterJob::AsyncExecute()
     return;
   }
 
+  // Push API, section 5: "When a service worker registration is unregistered,
+  // any associated push subscription must be deactivated." To ensure the
+  // service worker registration isn't cleared as we're unregistering, we
+  // unsubscribe first.
+  nsCOMPtr<nsIPushService> pushService =
+    do_GetService("@mozilla.org/push/Service;1");
+  if (NS_WARN_IF(!pushService)) {
+    Unregister();
+    return;
+  }
+  nsCOMPtr<nsIUnsubscribeResultCallback> unsubscribeCallback =
+    new PushUnsubscribeCallback(this);
+  nsresult rv = pushService->Unsubscribe(NS_ConvertUTF8toUTF16(mScope),
+                                         mPrincipal, unsubscribeCallback);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    Unregister();
+  }
+}
+
+void
+ServiceWorkerUnregisterJob::Unregister()
+{
+  AssertIsOnMainThread();
+
+  if (Canceled()) {
+    Finish(NS_ERROR_DOM_ABORT_ERR);
+    return;
+  }
+
   // Step 1 of the Unregister algorithm requires checking that the
   // client origin matches the scope's origin.  We perform this in
   // registration->update() method directly since we don't have that
diff --git a/dom/workers/ServiceWorkerUnregisterJob.h b/dom/workers/ServiceWorkerUnregisterJob.h
index 04a675c1195e..976f15a2cc64 100644
--- a/dom/workers/ServiceWorkerUnregisterJob.h
+++ b/dom/workers/ServiceWorkerUnregisterJob.h
@@ -24,11 +24,16 @@ public:
   GetResult() const;
 
 private:
+  class PushUnsubscribeCallback;
+
   virtual ~ServiceWorkerUnregisterJob();
 
   virtual void
   AsyncExecute() override;
 
+  void
+  Unregister();
+
   bool mResult;
   bool mSendToParent;
 };
