diff --git a/test/unit/modelmembers/test_spamvec.py b/test/unit/modelmembers/test_spamvec.py
index 4694fff4d..2b80225f0 100644
--- a/test/unit/modelmembers/test_spamvec.py
+++ b/test/unit/modelmembers/test_spamvec.py
@@ -306,7 +306,7 @@ def build_vec():
         return tppovm['1']  # complement POVM
 
     def test_vector_conversion(self):
-        with self.assertRaises(ValueError):
+        with self.assertRaises(RuntimeError):
             self.vec.to_vector()