diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..c4a2f00
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+.jshintrc
+*.swp
diff --git a/background.js b/background.js
index 78108ff..ad48312 100644
--- a/background.js
+++ b/background.js
@@ -1,8 +1,8 @@
-browser.idle.onStateChanged.addListener(function(state) {
+browser.idle.onStateChanged.addListener((state) => {
     if (state == 'idle') {
-        browser.storage.local.get('days', function(res) {
+        browser.storage.local.get('days').then((res) => {
             var days = res.days || 0;
-            if (days != 0) {
+            if (days !== 0) {
                 var end = new Date();
                 end.setHours(0);
                 end.setMinutes(0);
diff --git a/manifest.json b/manifest.json
index c570dfe..b22cfc9 100644
--- a/manifest.json
+++ b/manifest.json
@@ -3,6 +3,11 @@
     "name": "History Cleaner",
     "version": "1.1",
     "description": "Deletes history older than a specified amount of days.",
+    "applications": {
+        "gecko": {
+            "id": "{a138007c-5ff6-4d10-83d9-0afaf0efbe5e}"
+        }
+    },
     "icons": {
         "48": "icons/icon-48.png",
         "96": "icons/icon-96.png"
diff --git a/options.js b/options.js
index 7e0fd63..645b339 100644
--- a/options.js
+++ b/options.js
@@ -3,7 +3,7 @@ function saveOptions(e) {
     e.preventDefault();
 }
 function restoreOptions() {
-    browser.storage.local.get('days', function(res) {
+    browser.storage.local.get('days').then((res) => {
         document.querySelector("#days").value = res.days || 0;
     });
 }