diff --git a/tests/test_registation.py b/tests/test_registation.py
index 97af91d7..4037692b 100644
--- a/tests/test_registation.py
+++ b/tests/test_registation.py
@@ -58,7 +58,7 @@ def test_example(self):
             fixed=fixed, moving=moving, transformlist=mytx["fwdtransforms"], singleprecision=True
         )
         self.assertEqual(mywarpedimage2.pixeltype, moving.pixeltype)
-        self.assertAlmostEqual(mywarpedimage.sum(), mywarpedimage2.sum(), places=3)
+        self.assertLessEqual(np.sum((mywarpedimage.numpy() - mywarpedimage2.numpy()) ** 2), 0.1)
 
         # bad interpolator
         with self.assertRaises(Exception):