diff --git a/test/test_issue35.py b/test/test_issue35.py
index 4a43509..2890eb8 100644
--- a/test/test_issue35.py
+++ b/test/test_issue35.py
@@ -2,6 +2,6 @@
 
 
 # this should not segfault
-def test_issue35():
+def test_issue35() -> None:
     mat = cdd.matrix_from_array([[0, 0, 0]], rep_type=cdd.RepType.INEQUALITY)
     cdd.matrix_canonicalize(mat)