diff --git a/mslib/msui/viewwindows.py b/mslib/msui/viewwindows.py
index 8e75d9e6a..b85c178c8 100644
--- a/mslib/msui/viewwindows.py
+++ b/mslib/msui/viewwindows.py
@@ -76,7 +76,8 @@ def closeEvent(self, event):
         Overloads QtGui.QMainWindow.closeEvent(). This method is called if
         Qt receives a window close request for our application window.
         """
-        if self.mainwindow_signal_logout_mscolab is not None:
+        if self.docks[5] is not None and self.mainwindow_signal_logout_mscolab is not None:
+            # ToDo instead of numbers [5] use names
             # we need to disconnect the mainwindow_signal_logout when the topview is closed
             # the next topview will connect one again
             self.mainwindow_signal_logout_mscolab.disconnect()