diff --git a/openquake/hazardlib/tests/pmf_test.py b/openquake/hazardlib/tests/pmf_test.py
index d2f527fca4da..16426b6382e9 100644
--- a/openquake/hazardlib/tests/pmf_test.py
+++ b/openquake/hazardlib/tests/pmf_test.py
@@ -25,7 +25,7 @@ def test_creation(self):
 
     def test_wrong_sum(self):
         data = [(0.1, i) for i in range(10)]
-        self.assertRaises(ValueError, PMF, data, 1E-16)
+        self.assertRaises(ValueError, PMF, data, 1E-17)
 
     def test_empty_data(self):
         self.assertRaises(ValueError, PMF, [])