diff --git a/testing/test_mark.py b/testing/test_mark.py
index 5f3af52f4..19eff00f3 100644
--- a/testing/test_mark.py
+++ b/testing/test_mark.py
@@ -1111,7 +1111,7 @@ def test_pytest_param_id_allows_none_or_string(s) -> None:
     assert pytest.param(id=s)
 
 
-@pytest.mark.parametrize("expr", ("NOT internal_err", "NOT (internal_err)"))
+@pytest.mark.parametrize("expr", ("NOT internal_err", "NOT (internal_err)", "bogus="))
 def test_marker_expr_eval_failure_handling(pytester: Pytester, expr) -> None:
     foo = pytester.makepyfile(
         """