diff --git a/Core/Code/Testing/mitkVTKRenderWindowSizeTest.cpp b/Core/Code/Testing/mitkVTKRenderWindowSizeTest.cpp
index f5e2330dd5..c5a968808c 100644
--- a/Core/Code/Testing/mitkVTKRenderWindowSizeTest.cpp
+++ b/Core/Code/Testing/mitkVTKRenderWindowSizeTest.cpp
@@ -1,64 +1,65 @@
 /*===================================================================
 
 The Medical Imaging Interaction Toolkit (MITK)
 
 Copyright (c) German Cancer Research Center,
 Division of Medical and Biological Informatics.
 All rights reserved.
 
 This software is distributed WITHOUT ANY WARRANTY; without
 even the implied warranty of MERCHANTABILITY or FITNESS FOR
 A PARTICULAR PURPOSE.
 
 See LICENSE.txt or http://www.mitk.org for details.
 
 ===================================================================*/
 
 #include <vtkSmartPointer.h>
 #include <vtkRenderWindow.h>
 
 #include "mitkTestingMacros.h"
 
 void CheckRWSize(unsigned int width, unsigned int height)
 {
   MITK_TEST_OUTPUT(<<"Requesting VTK render window of size " << width << "x" << height );
   vtkSmartPointer<vtkRenderWindow> renderWindowVTK = vtkRenderWindow::New();
   renderWindowVTK->SetSize( width, height );
+  renderWindowVTK->SetOffScreenRendering(1); // seems to be related to off-screen rendering (only?)
 
   int* renderWindowSize = renderWindowVTK->GetSize();
 
   MITK_TEST_CONDITION( renderWindowSize[0] >= width, "  Window is at least " << width << "px wide (actually:" << renderWindowSize[0] << ")" );
   MITK_TEST_CONDITION( renderWindowSize[1] >= height, "  Window is at least " << height << "px high (actually:" << renderWindowSize[1] << ")" );
 }
 
 /**
   Check if a patch to VTK is applied as in http://paraview.org/Bug/view.php?id=14122
 
   Bug description from there:
 
   "
   After moving over to Visual Studio 2012, we found a strange problem where vtkRenderWindow GetSize()
   returns something different than what was provided to SetSize().
   Specifically, width and height are 8 pixels less than expected.
   I found a problem report which appears to describe what we are seeing. The problem goes away if we change the desktop theme to Windows Classic.
   "
 
   the patch from this bug should be applied to MITK's default VTK version.
 
   Test can be removed with VTK 6.
 */
 int mitkVTKRenderWindowSizeTest(int /*argc*/, char* /*argv*/[])
 {
   MITK_TEST_BEGIN("mitkVTKRenderWindowSizeTest")
 
   // some power of two default sizes
   CheckRWSize(128, 128);
   CheckRWSize(256, 256);
   CheckRWSize(512, 512);
 
   // some other size
   CheckRWSize(300, 200);
   CheckRWSize(150, 243);
 
   MITK_TEST_END()
 }