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)
diff --git a/test/test_linprog.py b/test/test_linprog.py
index dd8fa44..2c8ba76 100644
--- a/test/test_linprog.py
+++ b/test/test_linprog.py
@@ -1,4 +1,5 @@
 from collections.abc import Sequence
+from typing import Optional
 
 import pytest
 
@@ -123,7 +124,7 @@ def test_linprog_1(
     array: Sequence[Sequence[float]],
     obj_type: LPObjType,
     status: LPStatusType,
-    primal_solution: Sequence[float] | None,
+    primal_solution: Optional[Sequence[float]],
 ) -> None:
     lp = linprog_from_array(array, obj_type=obj_type)
     linprog_solve(lp)