diff --git a/atom/browser/lib/rpc-server.js b/atom/browser/lib/rpc-server.js
index f366eb43a52b..c3ea8ca6b094 100644
--- a/atom/browser/lib/rpc-server.js
+++ b/atom/browser/lib/rpc-server.js
@@ -11,8 +11,6 @@ const FUNCTION_PROPERTIES = [
   'length', 'name', 'arguments', 'caller', 'prototype',
 ];
 
-var slice = [].slice;
-
 // Return the description of object's members:
 let getObjectMemebers = function(object) {
   let names = Object.getOwnPropertyNames(object);
@@ -281,14 +279,13 @@ ipcMain.on('ATOM_BROWSER_CURRENT_WEB_CONTENTS', function(event) {
 });
 
 ipcMain.on('ATOM_BROWSER_CONSTRUCTOR', function(event, id, args) {
-  var constructor, obj;
   try {
     args = unwrapArgs(event.sender, args);
-    constructor = objectsRegistry.get(id);
+    let constructor = objectsRegistry.get(id);
 
     // Call new with array of arguments.
     // http://stackoverflow.com/questions/1606797/use-of-apply-with-new-operator-is-this-possible
-    obj = new (Function.prototype.bind.apply(constructor, [null].concat(args)));
+    let obj = new (Function.prototype.bind.apply(constructor, [null].concat(args)));
     return event.returnValue = valueToMeta(event.sender, obj);
   } catch (error) {
     return event.returnValue = exceptionToMeta(error);
@@ -296,10 +293,9 @@ ipcMain.on('ATOM_BROWSER_CONSTRUCTOR', function(event, id, args) {
 });
 
 ipcMain.on('ATOM_BROWSER_FUNCTION_CALL', function(event, id, args) {
-  var func;
   try {
     args = unwrapArgs(event.sender, args);
-    func = objectsRegistry.get(id);
+    let func = objectsRegistry.get(id);
     return callFunction(event, func, global, args);
   } catch (error) {
     return event.returnValue = exceptionToMeta(error);
@@ -307,13 +303,12 @@ ipcMain.on('ATOM_BROWSER_FUNCTION_CALL', function(event, id, args) {
 });
 
 ipcMain.on('ATOM_BROWSER_MEMBER_CONSTRUCTOR', function(event, id, method, args) {
-  var constructor, obj;
   try {
     args = unwrapArgs(event.sender, args);
-    constructor = objectsRegistry.get(id)[method];
+    let constructor = objectsRegistry.get(id)[method];
 
     // Call new with array of arguments.
-    obj = new (Function.prototype.bind.apply(constructor, [null].concat(args)));
+    let obj = new (Function.prototype.bind.apply(constructor, [null].concat(args)));
     return event.returnValue = valueToMeta(event.sender, obj);
   } catch (error) {
     return event.returnValue = exceptionToMeta(error);
@@ -321,10 +316,9 @@ ipcMain.on('ATOM_BROWSER_MEMBER_CONSTRUCTOR', function(event, id, method, args)
 });
 
 ipcMain.on('ATOM_BROWSER_MEMBER_CALL', function(event, id, method, args) {
-  var obj;
   try {
     args = unwrapArgs(event.sender, args);
-    obj = objectsRegistry.get(id);
+    let obj = objectsRegistry.get(id);
     return callFunction(event, obj[method], obj, args);
   } catch (error) {
     return event.returnValue = exceptionToMeta(error);
@@ -332,9 +326,8 @@ ipcMain.on('ATOM_BROWSER_MEMBER_CALL', function(event, id, method, args) {
 });
 
 ipcMain.on('ATOM_BROWSER_MEMBER_SET', function(event, id, name, value) {
-  var obj;
   try {
-    obj = objectsRegistry.get(id);
+    let obj = objectsRegistry.get(id);
     obj[name] = value;
     return event.returnValue = null;
   } catch (error) {
@@ -343,9 +336,8 @@ ipcMain.on('ATOM_BROWSER_MEMBER_SET', function(event, id, name, value) {
 });
 
 ipcMain.on('ATOM_BROWSER_MEMBER_GET', function(event, id, name) {
-  var obj;
   try {
-    obj = objectsRegistry.get(id);
+    let obj = objectsRegistry.get(id);
     return event.returnValue = valueToMeta(event.sender, obj[name]);
   } catch (error) {
     return event.returnValue = exceptionToMeta(error);
@@ -357,21 +349,18 @@ ipcMain.on('ATOM_BROWSER_DEREFERENCE', function(event, id) {
 });
 
 ipcMain.on('ATOM_BROWSER_GUEST_WEB_CONTENTS', function(event, guestInstanceId) {
-  var guestViewManager;
   try {
-    guestViewManager = require('./guest-view-manager');
+    let guestViewManager = require('./guest-view-manager');
     return event.returnValue = valueToMeta(event.sender, guestViewManager.getGuest(guestInstanceId));
   } catch (error) {
     return event.returnValue = exceptionToMeta(error);
   }
 });
 
-ipcMain.on('ATOM_BROWSER_ASYNC_CALL_TO_GUEST_VIEW', function() {
-  var args, event, guest, guestInstanceId, guestViewManager, method;
-  event = arguments[0], guestInstanceId = arguments[1], method = arguments[2], args = 4 <= arguments.length ? slice.call(arguments, 3) : [];
+ipcMain.on('ATOM_BROWSER_ASYNC_CALL_TO_GUEST_VIEW', function(event, guestInstanceId, method, ...args) {
   try {
-    guestViewManager = require('./guest-view-manager');
-    guest = guestViewManager.getGuest(guestInstanceId);
+    let guestViewManager = require('./guest-view-manager');
+    let guest = guestViewManager.getGuest(guestInstanceId);
     return guest[method].apply(guest, args);
   } catch (error) {
     return event.returnValue = exceptionToMeta(error);