diff --git a/rdkit/Chem/Draw/UnitTestSimilarityMaps.py b/rdkit/Chem/Draw/UnitTestSimilarityMaps.py

index 3b85450..9f39c92 100755

--- a/rdkit/Chem/Draw/UnitTestSimilarityMaps.py

+++ b/rdkit/Chem/Draw/UnitTestSimilarityMaps.py

@@ -98,6 +98,7 @@ class TestCase(unittest.TestCase):

 if __name__ == '__main__':

   try:

     import matplotlib

+    matplotlib.use('cairo')

     from rdkit.Chem.Draw.mplCanvas import Canvas

   except ImportError:

     pass