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