diff --git a/package.json b/package.json
index b1a5c7e89..46d7f7de9 100644
--- a/package.json
+++ b/package.json
@@ -13,7 +13,7 @@
     "prettier": "prettier --single-quote --trailing-comma es5 --write 'src/**/*.{js,ts,tsx}'",
     "jest": "jest",
     "test": "yarn jest",
-    "start": "electron . –enable-logging"
+    "start": "electron . -–enable-logging"
   },
   "repository": {
     "type": "git",
diff --git a/src/js/components/notification.tsx b/src/js/components/notification.tsx
index f6643a9d9..552875c80 100644
--- a/src/js/components/notification.tsx
+++ b/src/js/components/notification.tsx
@@ -79,8 +79,11 @@ export const NotificationItem: React.FC<IProps> = (props) => {
   };
 
   const openBrowser = () => {
-    const url = generateGitHubWebUrl(props.notification.subject.url);
-    shell.openExternal(url);
+    // Some Notification types from GitHub are missing urls in their subjects.
+    if (props.notification.subject.url) {
+      const url = generateGitHubWebUrl(props.notification.subject.url);
+      shell.openExternal(url);
+    }
   };
 
   const markAsRead = () => {
diff --git a/src/js/utils/helpers.ts b/src/js/utils/helpers.ts
index ca4fd13d2..fac12063e 100644
--- a/src/js/utils/helpers.ts
+++ b/src/js/utils/helpers.ts
@@ -7,7 +7,7 @@ import Constants from './constants';
 import { loginUser } from '../actions';
 import { AuthState } from '../../types/reducers';
 
-export function getEnterpriseAccountToken(hostname, accounts) {
+export function getEnterpriseAccountToken(hostname, accounts): string {
   return accounts.find((obj) => obj.hostname === hostname).token;
 }
 
@@ -18,12 +18,12 @@ export function generateGitHubAPIUrl(hostname) {
     : `https://api.${hostname}/`;
 }
 
-export function generateGitHubWebUrl(url) {
+export function generateGitHubWebUrl(url: string) {
   const { hostname } = parse(url);
   const isEnterprise =
     hostname !== `api.${Constants.DEFAULT_AUTH_OPTIONS.hostname}`;
 
-  let newUrl = isEnterprise
+  let newUrl: string = isEnterprise
     ? url.replace(`${hostname}/api/v3/repos`, hostname)
     : url.replace('api.github.com/repos', 'github.com');
 
diff --git a/src/js/utils/notifications.ts b/src/js/utils/notifications.ts
index a41abc4ad..b8f758197 100644
--- a/src/js/utils/notifications.ts
+++ b/src/js/utils/notifications.ts
@@ -2,11 +2,15 @@ const { remote } = require('electron');
 
 import { generateGitHubWebUrl } from '../utils/helpers';
 import { reOpenWindow, openExternalLink } from '../utils/comms';
-import { SubjectType } from '../../types/github';
+import { Notification } from '../../types/github';
 import { SettingsState } from '../../types/reducers';
 
 export default {
-  setup(notifications, notificationsCount, settings: SettingsState) {
+  setup(
+    notifications: Notification[],
+    notificationsCount,
+    settings: SettingsState
+  ) {
     // If there are no new notifications just stop there
     if (!notificationsCount) {
       return;
@@ -21,11 +25,15 @@ export default {
     }
   },
 
-  raiseNativeNotification(notifications, count) {
-    let title, body, icon, notificationUrl;
+  raiseNativeNotification(notifications, count: number) {
+    let title: string;
+    let body: string;
+    let notificationUrl: string | null;
 
     if (count === 1) {
-      const notification = notifications.find((obj) => obj.length > 0)[0];
+      const notification: Notification = notifications.find(
+        (obj) => obj.length > 0
+      )[0];
       title = `Gitify - ${notification.repository.full_name}`;
       body = notification.subject.title;
       notificationUrl = notification.subject.url;
@@ -42,10 +50,13 @@ export default {
     nativeNotification.onclick = function () {
       if (count === 1) {
         const appWindow = remote.getCurrentWindow();
-        const url = generateGitHubWebUrl(notificationUrl);
-
         appWindow.hide();
-        openExternalLink(url);
+
+        // Some Notification types from GitHub are missing urls in their subjects.
+        if (notificationUrl) {
+          const url = generateGitHubWebUrl(notificationUrl);
+          openExternalLink(url);
+        }
       } else {
         reOpenWindow();
       }