diff --git a/py-polars/polars/io/delta.py b/py-polars/polars/io/delta.py
index 91c61a4ef368..ed0a9b95c113 100644
--- a/py-polars/polars/io/delta.py
+++ b/py-polars/polars/io/delta.py
@@ -338,6 +338,9 @@ def _check_if_delta_available() -> None:
 def _check_for_unsupported_types(dtypes: list[DataType]) -> None:
     schema_dtypes = unpack_dtypes(*dtypes)
     unsupported_types = {Time, Null}
+    # Note that this overlap check does NOT work correctly for Categorical, so
+    # if Categorical is added back to unsupported_types a different check will
+    # need to be used.
     overlap = schema_dtypes & unsupported_types
 
     if overlap: