diff --git a/tests/test_metrics.py b/tests/test_metrics.py
index 2f29cf2..959e6d8 100644
--- a/tests/test_metrics.py
+++ b/tests/test_metrics.py
@@ -82,7 +82,7 @@ def test_summary_aliases_match_canonical_fields() -> None:
     [annualized_return, annualized_volatility, sharpe_ratio, max_drawdown, calmar_ratio, win_rate],
 )
 def test_metrics_reject_non_series_input(metric) -> None:
-    with pytest.raises(TypeError, match="expected pd.Series"):
+    with pytest.raises(TypeError, match=r"expected pd\.Series"):
         metric([0.01, 0.02])