diff --git a/tests/logprob/test_transforms.py b/tests/logprob/test_transforms.py
index 1f9fc838a6..b55699b569 100644
--- a/tests/logprob/test_transforms.py
+++ b/tests/logprob/test_transforms.py
@@ -288,7 +288,7 @@ def test_loc_transform_rv(self, rv_size, loc_type, addition):
     @pytest.mark.parametrize(
         "rv_size, scale_type, product",
         [
-            (None, pt.scalar, True),
+            ((), pt.scalar, True),
             (1, pt.TensorType("floatX", (True,)), True),
             ((2, 3), pt.matrix, False),
         ],