diff --git a/lib/notification-reducer.js b/lib/notification-reducer.js
index b1f5c85..dc0ed1a 100644
--- a/lib/notification-reducer.js
+++ b/lib/notification-reducer.js
@@ -21,7 +21,7 @@ export class NotificationReducer {
 
   get notificationsForReassignedPRs() {
     return this.notificationsWithPullRequests.filter((notification) => {
-      return notification.reason === "subscribed" && notification.pull_request.assignee != this.me && notification.pull_request.assignee != ""
+      return notification.reason === "subscribed" && notification.pull_request.assignee != this.me && notification.pull_request.assignee !== null
     });
   }
 
diff --git a/test/fixtures/pr21.json b/test/fixtures/pr21.json
index 8b93dca..44cc4ab 100644
--- a/test/fixtures/pr21.json
+++ b/test/fixtures/pr21.json
@@ -4,6 +4,7 @@
   "number": 21,
   "state": "closed",
   "title": "Add support for resource-specific tags",
+  "assignee": null,
   "user": {
     "login": "jansiwy",
     "id": 610800,
diff --git a/test/fixtures/pr45.json b/test/fixtures/pr45.json
index 6bf8f70..7bd3e86 100644
--- a/test/fixtures/pr45.json
+++ b/test/fixtures/pr45.json
@@ -4,6 +4,7 @@
   "number": 45,
   "state": "open",
   "title": "Breaking change: Unify support for resource-specific tags",
+  "assignee": "jansiwy",
   "user": {
     "login": "jansiwy",
     "id": 610800,
diff --git a/test/reducer.js b/test/reducer.js
index e28eeb7..815958a 100644
--- a/test/reducer.js
+++ b/test/reducer.js
@@ -46,6 +46,7 @@ describe('Reducer', async () => {
       'number',
       'state',
       'title',
+      'assignee',
       'user',
       'body',
       'created_at',