diff --git a/AppKit/Platform/CPPlatformWindow.j b/AppKit/Platform/CPPlatformWindow.j
index fb742b351..de2080bcc 100644
--- a/AppKit/Platform/CPPlatformWindow.j
+++ b/AppKit/Platform/CPPlatformWindow.j
@@ -213,7 +213,7 @@ var PrimaryPlatformWindow   = NULL;
 - (BOOL)isVisible
 {
 #if PLATFORM(DOM)
-    return _DOMWindow !== NULL;
+    return _DOMWindow !== NULL && _DOMWindow !== undefined;
 #else
     return NO;
 #endif
diff --git a/AppKit/Platform/DOM/CPPlatformWindow+DOM.j b/AppKit/Platform/DOM/CPPlatformWindow+DOM.j
index e96a5708c..bb183bd99 100644
--- a/AppKit/Platform/DOM/CPPlatformWindow+DOM.j
+++ b/AppKit/Platform/DOM/CPPlatformWindow+DOM.j
@@ -568,6 +568,9 @@ _CPPlatformWindowWillCloseNotification = @"_CPPlatformWindowWillCloseNotificatio
 
     _DOMWindow = window.open("about:blank", "_blank", "menubar=no,location=no,resizable=yes,scrollbars=no,status=no,left=" + CGRectGetMinX(_contentRect) + ",top=" + CGRectGetMinY(_contentRect) + ",width=" + CGRectGetWidth(_contentRect) + ",height=" + CGRectGetHeight(_contentRect));
 
+    if (!_DOMWindow)
+        return;
+
     [PlatformWindows addObject:self];
 
     // FIXME: cpSetFrame?
@@ -1414,6 +1417,9 @@ _CPPlatformWindowWillCloseNotification = @"_CPPlatformWindowWillCloseNotificatio
 
 - (void)order:(CPWindowOrderingMode)orderingMode window:(CPWindow)aWindow relativeTo:(CPWindow)otherWindow
 {
+    if (!_DOMWindow)
+        return;
+
     [CPPlatform initializeScreenIfNecessary];
 
     // Grab the appropriate level for the layer, and create it if