diff --git a/tests/_stats/test_aggregation.py b/tests/_stats/test_aggregation.py
index c2a030886e..08291d449b 100644
--- a/tests/_stats/test_aggregation.py
+++ b/tests/_stats/test_aggregation.py
@@ -89,7 +89,7 @@ def test_mean_sd(self, df, func):
 
         grouped = df.groupby("x", as_index=False)["y"]
         est = grouped.mean()
-        err = grouped.std()
+        err = grouped.std().fillna(0)  # fillna needed only on pinned tests
         expected = est.assign(ymin=est["y"] - err["y"], ymax=est["y"] + err["y"])
         assert_frame_equal(res, expected)