diff --git a/lib/browser/guest-view-manager.js b/lib/browser/guest-view-manager.js
index 9fffb745ac..a0bc751813 100644
--- a/lib/browser/guest-view-manager.js
+++ b/lib/browser/guest-view-manager.js
@@ -4,9 +4,9 @@ const ipcMain = require('electron').ipcMain
 const webContents = require('electron').webContents
 
 // Doesn't exist in early initialization.
-var webViewManager = null
+let webViewManager = null
 
-var supportedWebViewEvents = [
+const supportedWebViewEvents = [
   'load-commit',
   'did-finish-load',
   'did-fail-load',
@@ -40,23 +40,23 @@ var supportedWebViewEvents = [
   'update-target-url'
 ]
 
-var nextInstanceId = 0
-var guestInstances = {}
-var embedderElementsMap = {}
-var reverseEmbedderElementsMap = {}
+let nextInstanceId = 0
+const guestInstances = {}
+const embedderElementsMap = {}
+const reverseEmbedderElementsMap = {}
 
 // Moves the last element of array to the first one.
-var moveLastToFirst = function (list) {
+const moveLastToFirst = function (list) {
   return list.unshift(list.pop())
 }
 
 // Generate guestInstanceId.
-var getNextInstanceId = function () {
+const getNextInstanceId = function () {
   return ++nextInstanceId
 }
 
 // Create a new guest instance.
-var createGuest = function (embedder, params) {
+const createGuest = function (embedder, params) {
   if (webViewManager == null) {
     webViewManager = process.atomBinding('web_view_manager')
   }
@@ -98,7 +98,7 @@ var createGuest = function (embedder, params) {
 
   // Init guest web view after attached.
   guest.once('did-attach', function () {
-    var opts
+    let opts
     params = this.attachParams
     delete this.attachParams
     this.viewInstanceId = params.instanceId
@@ -154,8 +154,8 @@ var createGuest = function (embedder, params) {
 }
 
 // Attach the guest to an element of embedder.
-var attachGuest = function (embedder, elementInstanceId, guestInstanceId, params) {
-  var guest, key, oldGuestInstanceId, ref1, webPreferences
+const attachGuest = function (embedder, elementInstanceId, guestInstanceId, params) {
+  let guest, key, oldGuestInstanceId, ref1, webPreferences
   guest = guestInstances[guestInstanceId].guest
 
   // Destroy the old guest when attaching.
@@ -190,12 +190,12 @@ var attachGuest = function (embedder, elementInstanceId, guestInstanceId, params
 }
 
 // Destroy an existing guest instance.
-var destroyGuest = function (embedder, id) {
-  var key
+const destroyGuest = function (embedder, id) {
   webViewManager.removeGuest(embedder, id)
   guestInstances[id].guest.destroy()
   delete guestInstances[id]
-  key = reverseEmbedderElementsMap[id]
+
+  const key = reverseEmbedderElementsMap[id]
   if (key != null) {
     delete reverseEmbedderElementsMap[id]
     return delete embedderElementsMap[key]
@@ -215,18 +215,18 @@ ipcMain.on('ELECTRON_GUEST_VIEW_MANAGER_DESTROY_GUEST', function (event, id) {
 })
 
 ipcMain.on('ELECTRON_GUEST_VIEW_MANAGER_SET_SIZE', function (event, id, params) {
-  var ref1
-  return (ref1 = guestInstances[id]) != null ? ref1.guest.setSize(params) : void 0
+  const guestInstance = guestInstances[id]
+  return guestInstance != null ? guestInstance.guest.setSize(params) : void 0
 })
 
 // Returns WebContents from its guest id.
 exports.getGuest = function (id) {
-  var ref1
-  return (ref1 = guestInstances[id]) != null ? ref1.guest : void 0
+  const guestInstance = guestInstances[id]
+  return guestInstance != null ? guestInstance.guest : void 0
 }
 
 // Returns the embedder of the guest.
 exports.getEmbedder = function (id) {
-  var ref1
-  return (ref1 = guestInstances[id]) != null ? ref1.embedder : void 0
+  const guestInstance = guestInstances[id]
+  return guestInstance != null ? guestInstance.embedder : void 0
 }