diff --git a/tests/hazmat/primitives/test_rsa.py b/tests/hazmat/primitives/test_rsa.py
index 7cf6e2f..032ed47 100644
--- a/tests/hazmat/primitives/test_rsa.py
+++ b/tests/hazmat/primitives/test_rsa.py
@@ -95,7 +95,7 @@
 @pytest.mark.rsa
 class TestRSA(object):
     @pytest.mark.parametrize(
-        "public_exponent,key_size",
+        ("public_exponent", "key_size"),
         itertools.product(
             (3, 5, 65537),
             (1024, 1025, 1026, 1027, 1028, 1029, 1030, 1031, 1536, 2048)