diff --git a/python/cudf_polars/cudf_polars/dsl/ir.py b/python/cudf_polars/cudf_polars/dsl/ir.py
index 37f4805e562..41a2b5880e3 100644
--- a/python/cudf_polars/cudf_polars/dsl/ir.py
+++ b/python/cudf_polars/cudf_polars/dsl/ir.py
@@ -1654,7 +1654,7 @@ class MergeSorted(IR):
     """Merge sorted operation."""
 
     __slots__ = ("key",)
-    _non_child = ("key",)
+    _non_child = ("schema", "key")
     key: str
     """Key that is sorted."""