diff --git a/direct/src/showbase/ShowBase.py b/direct/src/showbase/ShowBase.py
index c0e6d9dd16..ddb7fb48d8 100644
--- a/direct/src/showbase/ShowBase.py
+++ b/direct/src/showbase/ShowBase.py
@@ -829,9 +829,10 @@ class ShowBase(DirectObject.DirectObject):
             win.requestProperties(props)
 
         mainWindow = False
-        if self.win == None:
+        if self.win is None:
             mainWindow = True
             self.win = win
+            self.bufferViewer.win = win
 
         self.winList.append(win)