diff --git a/test/test_serialization.py b/test/test_serialization.py
index 00c08cc..47c45e8 100644
--- a/test/test_serialization.py
+++ b/test/test_serialization.py
@@ -42,7 +42,7 @@ def test_roundtrip_bytes(all_types):
     msg = all_types.TestAllTypes.from_bytes(message_bytes)
     test_regression.check_all_types(msg)
 
-@pytest.mark.skipif(sys.version_info.major < 3, reason="mmap doesn't implement the buffer interface under python 2.")
+@pytest.mark.skipif(sys.version_info[0] < 3, reason="mmap doesn't implement the buffer interface under python 2.")
 def test_roundtrip_bytes_mmap(all_types):
     msg = all_types.TestAllTypes.new_message()
     test_regression.init_all_types(msg)