diff --git a/python/mlcroissant/mlcroissant/_src/operation_graph/operations/field.py b/python/mlcroissant/mlcroissant/_src/operation_graph/operations/field.py
index 79f27e41a..d9b3ae5b3 100644
--- a/python/mlcroissant/mlcroissant/_src/operation_graph/operations/field.py
+++ b/python/mlcroissant/mlcroissant/_src/operation_graph/operations/field.py
@@ -118,4 +118,4 @@ def __call__(self, df: pd.DataFrame) -> pd.Series:
         series = _name_series(value, self.node)
         transforms = functools.partial(apply_transforms_fn, source=self.node.source)
         cast = functools.partial(_cast_value, data_type=self.node.data_type)
-        return series.apply(transforms).apply(cast)
+        return pd.Series(series.apply(transforms).apply(cast))