Index: lib/prefs.js
diff --git a/lib/prefs.js b/lib/prefs.js
index e1aa3f751c5feb430e5dfb83ada7917bd777bd9f..632e3aa03936d8d10a02cfbc8ecd92b58f9721af 100644
--- a/lib/prefs.js
+++ b/lib/prefs.js
@@ -17,7 +17,9 @@
 
 /** @module prefs */
 
-let {EventEmitter} = require("events");
+"use strict";
+
+const {EventEmitter} = require("events");
 
 const keyPrefix = "pref:";
 
@@ -188,7 +190,7 @@ let Prefs = exports.Prefs = {
    * @param {string}   preference
    * @param {function} callback
    */
-  on: function(preference, callback)
+  on(preference, callback)
   {
     eventEmitter.on(preference, callback);
   },
@@ -199,7 +201,7 @@ let Prefs = exports.Prefs = {
    * @param {string}   preference
    * @param {function} callback
    */
-  off: function(preference, callback)
+  off(preference, callback)
   {
     eventEmitter.off(preference, callback);
   },
@@ -230,11 +232,8 @@ function prefToKey(pref)
 function addPreference(pref)
 {
   Object.defineProperty(Prefs, pref, {
-    get: function()
-    {
-      return (pref in overrides ? overrides : defaults)[pref];
-    },
-    set: function(value)
+    get() { return (pref in overrides ? overrides : defaults)[pref]; },
+    set(value)
     {
       let defaultValue = defaults[pref];
 
@@ -262,7 +261,7 @@ function init()
   prefs.forEach(addPreference);
 
   let localLoaded = new Promise(resolve => {
-    ext.storage.get(prefs.map(prefToKey), function(items)
+    ext.storage.get(prefs.map(prefToKey), items =>
     {
       for (let key in items)
         overrides[keyToPref(key)] = items[key];
@@ -274,7 +273,7 @@ function init()
   let managedLoaded = new Promise(resolve => {
     if (require("info").platform == "chromium" && "managed" in chrome.storage)
     {
-      chrome.storage.managed.get(null, function(items)
+      chrome.storage.managed.get(null, items =>
       {
         // Opera doesn't support chrome.storage.managed, but instead simply
         // removing the API, Opera sets chrome.runtime.lastError when using it.
@@ -296,7 +295,7 @@ function init()
 
   function onLoaded()
   {
-    ext.storage.onChanged.addListener(function(changes)
+    ext.storage.onChanged.addListener(changes =>
     {
       for (let key in changes)
       {