diff --git a/widget/src/cocoa/nsCocoaWindow.mm b/widget/src/cocoa/nsCocoaWindow.mm
index 7018739870a4..7a5959f0d147 100644
--- a/widget/src/cocoa/nsCocoaWindow.mm
+++ b/widget/src/cocoa/nsCocoaWindow.mm
@@ -65,9 +65,6 @@ extern BOOL                gSomeMenuBarPainted;
 
 #define NS_APPSHELLSERVICE_CONTRACTID "@mozilla.org/appshell/appShellService;1"
 
-// call getHiddenWindowNativeMenu, don't use this directly
-static nsIMenuBar* gHiddenWindowMenuBar;
-
 NS_IMPL_ISUPPORTS_INHERITED1(nsCocoaWindow, Inherited, nsPIWidgetCocoa)
 
 
@@ -157,9 +154,6 @@ nsCocoaWindow::~nsCocoaWindow()
 
 static nsIMenuBar* GetHiddenWindowMenuBar()
 {
-  if (gHiddenWindowMenuBar)
-    return gHiddenWindowMenuBar;
-  
   nsCOMPtr<nsIAppShellService> appShell(do_GetService(NS_APPSHELLSERVICE_CONTRACTID));
   if (!appShell) {
     NS_WARNING("Couldn't get AppShellService in order to get hidden window ref");
@@ -169,7 +163,7 @@ static nsIMenuBar* GetHiddenWindowMenuBar()
   nsCOMPtr<nsIXULWindow> hiddenWindow;
   appShell->GetHiddenWindow(getter_AddRefs(hiddenWindow));
   if (!hiddenWindow) {
-    NS_WARNING("Couldn't get hidden window from appshell");
+    // Don't warn, this happens during shutdown, bug 358607.
     return nsnull;
   }
   
@@ -187,13 +181,7 @@ static nsIMenuBar* GetHiddenWindowMenuBar()
   }
   
   nsIWidget* hiddenWindowWidgetNoCOMPtr = hiddenWindowWidget;
-  nsIMenuBar* geckoMenuBar = NS_STATIC_CAST(nsCocoaWindow*, hiddenWindowWidgetNoCOMPtr)->GetMenuBar();  
-  
-  if (geckoMenuBar) {
-    gHiddenWindowMenuBar = geckoMenuBar;
-  }
-  
-  return gHiddenWindowMenuBar;
+  return NS_STATIC_CAST(nsCocoaWindow*, hiddenWindowWidgetNoCOMPtr)->GetMenuBar();  
 }
 
 
diff --git a/xpfe/appshell/src/nsAppShellService.cpp b/xpfe/appshell/src/nsAppShellService.cpp
index 6f4137d8cce5..0463d2408b29 100644
--- a/xpfe/appshell/src/nsAppShellService.cpp
+++ b/xpfe/appshell/src/nsAppShellService.cpp
@@ -151,7 +151,7 @@ nsAppShellService::CreateHiddenWindow(nsIAppShell* aAppShell)
   nsresult rv;
   PRInt32 initialHeight = 100, initialWidth = 100;
     
-#if defined(XP_MAC) || defined(XP_MACOSX)
+#ifdef XP_MACOSX
   static const char defaultHiddenWindowURL[] = "chrome://global/content/hiddenWindow.xul";
   PRUint32    chromeMask = 0;
   nsCOMPtr<nsIPrefBranch> prefBranch;
@@ -177,7 +177,7 @@ nsAppShellService::CreateHiddenWindow(nsIAppShell* aAppShell)
 
   mHiddenWindow.swap(newWindow);
 
-#if defined(XP_MAC) || defined(XP_MACOSX)
+#ifdef XP_MACOSX
   // hide the hidden window by launching it into outer space. This
   // way, we can keep it visible and let the OS send it activates
   // to keep menus happy. This will cause it to show up in window
@@ -253,7 +253,7 @@ nsAppShellService::CalculateWindowZLevel(nsIXULWindow *aParent,
   else if (aChromeMask & nsIWebBrowserChrome::CHROME_WINDOW_LOWERED)
     zLevel = nsIXULWindow::loweredZ;
 
-#if defined(XP_MAC) || defined(XP_MACOSX)
+#ifdef XP_MACOSX
   /* Platforms on which modal windows are always application-modal, not
      window-modal (that's just the Mac, right?) want modal windows to
      be stacked on top of everyone else.
@@ -502,6 +502,11 @@ nsAppShellService::UnregisterTopLevelWindow(nsIXULWindow* aWindow)
   
   NS_ENSURE_ARG_POINTER(aWindow);
 
+  if (aWindow == mHiddenWindow) {
+    // CreateHiddenWindow() does not register the window, so we're done.
+    return NS_OK;
+  }
+
   // tell the window mediator
   nsCOMPtr<nsIWindowMediator> mediator
     ( do_GetService(NS_WINDOWMEDIATOR_CONTRACTID) );