diff --git a/atom/browser/api/lib/browser-window.coffee b/atom/browser/api/lib/browser-window.coffee
index 15411fb85769..1aa84bb15c48 100644
--- a/atom/browser/api/lib/browser-window.coffee
+++ b/atom/browser/api/lib/browser-window.coffee
@@ -1,14 +1,10 @@
 EventEmitter = require('events').EventEmitter
-IDWeakMap = process.atomBinding('id_weak_map').IDWeakMap
 app = require 'app'
 ipc = require 'ipc'
 
 BrowserWindow = process.atomBinding('window').BrowserWindow
 BrowserWindow::__proto__ = EventEmitter.prototype
 
-# Store all created windows in the weak map.
-BrowserWindow.windows = new IDWeakMap
-
 BrowserWindow::_init = ->
   # Simulate the application menu on platforms other than OS X.
   if process.platform isnt 'darwin'
@@ -31,11 +27,6 @@ BrowserWindow::_init = ->
   @on 'focus', (event) =>
     app.emit 'browser-window-focus', event, this
 
-  # Remove the window from weak map immediately when it's destroyed, since we
-  # could be iterating windows before GC happened.
-  @once 'closed', =>
-    BrowserWindow.windows.remove @id if BrowserWindow.windows.has @id
-
 BrowserWindow::setMenu = (menu) ->
   throw new TypeError('Invalid menu') unless menu is null or menu?.constructor?.name is 'Menu'
 
diff --git a/atom/browser/lib/guest-window-manager.coffee b/atom/browser/lib/guest-window-manager.coffee
index aef8b0def24d..e26c93513c9c 100644
--- a/atom/browser/lib/guest-window-manager.coffee
+++ b/atom/browser/lib/guest-window-manager.coffee
@@ -48,17 +48,14 @@ ipc.on 'ATOM_SHELL_GUEST_WINDOW_MANAGER_WINDOW_OPEN', (event, args...) ->
     event.returnValue = createGuest event.sender, args...
 
 ipc.on 'ATOM_SHELL_GUEST_WINDOW_MANAGER_WINDOW_CLOSE', (event, guestId) ->
-  return unless BrowserWindow.windows.has guestId
-  BrowserWindow.windows.get(guestId).destroy()
+  BrowserWindow.fromId(guestId)?.destroy()
 
 ipc.on 'ATOM_SHELL_GUEST_WINDOW_MANAGER_WINDOW_METHOD', (event, guestId, method, args...) ->
-  return unless BrowserWindow.windows.has guestId
-  BrowserWindow.windows.get(guestId)[method] args...
+  BrowserWindow.fromId(guestId)?[method] args...
 
 ipc.on 'ATOM_SHELL_GUEST_WINDOW_MANAGER_WINDOW_POSTMESSAGE', (event, guestId, message, targetOrigin) ->
-  return unless BrowserWindow.windows.has guestId
-  guestContents = BrowserWindow.windows.get(guestId).webContents
-  if guestContents.getUrl().indexOf(targetOrigin) is 0 or targetOrigin is '*'
+  guestContents = BrowserWindow.fromId(guestId)?.webContents
+  if guestContents?.getUrl().indexOf(targetOrigin) is 0 or targetOrigin is '*'
     guestContents.send 'ATOM_SHELL_GUEST_WINDOW_POSTMESSAGE', message, targetOrigin
 
 ipc.on 'ATOM_SHELL_GUEST_WINDOW_MANAGER_WINDOW_OPENER_POSTMESSAGE', (event, message, targetOrigin) ->
@@ -67,5 +64,4 @@ ipc.on 'ATOM_SHELL_GUEST_WINDOW_MANAGER_WINDOW_OPENER_POSTMESSAGE', (event, mess
     embedder.send 'ATOM_SHELL_GUEST_WINDOW_POSTMESSAGE', message, targetOrigin
 
 ipc.on 'ATOM_SHELL_GUEST_WINDOW_MANAGER_WEB_CONTENTS_METHOD', (event, guestId, method, args...) ->
-  return unless BrowserWindow.windows.has guestId
-  BrowserWindow.windows.get(guestId).webContents?[method] args...
+  BrowserWindow.fromId(guestId)?.webContents?[method] args...