diff --git a/src/tests/test_polars.py b/src/tests/test_polars.py
index 495defb7c..68d5bb9b7 100644
--- a/src/tests/test_polars.py
+++ b/src/tests/test_polars.py
@@ -93,10 +93,30 @@
 
 
 class TestAppendDataClass:
+    @given(
+        data=fixed_dictionaries({
+            "a": int64s() | none(),
+            "b": floats() | none(),
+            "c": text_ascii() | none(),
+        })
+    )
+    def test_columns_and_fields_equal(self, *, data: StrMapping) -> None:
+        df = DataFrame(schema={"a": Int64, "b": Float64, "c": Utf8})
+
+        @dataclass(kw_only=True)
+        class Row:
+            a: int | None = None
+            b: float | None = None
+            c: str | None = None
+
+        row = Row(**data)
+        result = append_dataclass(df, row)
+        height = 0 if (row.a is None) and (row.b is None) and (row.c is None) else 1
+        check_polars_dataframe(result, height=height, schema_list=df.schema)
+
     @given(data=fixed_dictionaries({"a": int64s() | none(), "b": floats() | none()}))
-    def test_main(self, *, data: StrMapping) -> None:
-        schema = {"a": Int64, "b": Float64, "c": Utf8}
-        df = DataFrame([], schema=schema, orient="row")
+    def test_extra_column(self, *, data: StrMapping) -> None:
+        df = DataFrame(schema={"a": Int64, "b": Float64, "c": Utf8})
 
         @dataclass(kw_only=True)
         class Row:
@@ -105,12 +125,27 @@ class Row:
 
         row = Row(**data)
         result = append_dataclass(df, row)
-        check_polars_dataframe(result, height=1, schema_list=schema)
+        height = 0 if (row.a is None) and (row.b is None) else 1
+        check_polars_dataframe(result, height=height, schema_list=df.schema)
+
+    @given(data=fixed_dictionaries({"a": int64s() | none(), "b": floats() | none()}))
+    def test_extra_field_but_none(self, *, data: StrMapping) -> None:
+        df = DataFrame(schema={"a": Int64, "b": Float64})
+
+        @dataclass(kw_only=True)
+        class Row:
+            a: int | None = None
+            b: float | None = None
+            c: str | None = None
+
+        row = Row(**data)
+        result = append_dataclass(df, row)
+        height = 0 if (row.a is None) and (row.b is None) else 1
+        check_polars_dataframe(result, height=height, schema_list=df.schema)
 
     @given(data=fixed_dictionaries({"datetime": zoned_datetimes()}))
     def test_zoned_datetime(self, *, data: StrMapping) -> None:
-        schema = {"datetime": DatetimeUTC}
-        df = DataFrame([], schema=schema, orient="row")
+        df = DataFrame(schema={"datetime": DatetimeUTC})
 
         @dataclass(kw_only=True)
         class Row:
@@ -118,23 +153,23 @@ class Row:
 
         row = Row(**data)
         result = append_dataclass(df, row)
-        check_polars_dataframe(result, height=1, schema_list=schema)
+        check_polars_dataframe(result, height=1, schema_list=df.schema)
 
     @given(
         data=fixed_dictionaries({
             "a": int64s() | none(),
             "b": floats() | none(),
-            "c": text_ascii() | none(),
+            "c": text_ascii(),
         })
     )
     def test_error(self, *, data: StrMapping) -> None:
-        df = DataFrame([], schema={"a": Int64, "b": Float64}, orient="row")
+        df = DataFrame(schema={"a": Int64, "b": Float64})
 
         @dataclass(kw_only=True)
         class Row:
             a: int | None = None
             b: float | None = None
-            c: str | None = None
+            c: str
 
         row = Row(**data)
         with raises(
diff --git a/src/utilities/__init__.py b/src/utilities/__init__.py
index c28d54135..c3dc96e8e 100644
--- a/src/utilities/__init__.py
+++ b/src/utilities/__init__.py
@@ -1,3 +1,3 @@
 from __future__ import annotations
 
-__version__ = "0.57.3"
+__version__ = "0.57.4"
diff --git a/src/utilities/polars.py b/src/utilities/polars.py
index 87b7a410c..09de91281 100644
--- a/src/utilities/polars.py
+++ b/src/utilities/polars.py
@@ -5,7 +5,7 @@
 from collections.abc import Callable, Iterable, Iterator, Mapping, Sequence
 from collections.abc import Set as AbstractSet
 from contextlib import suppress
-from dataclasses import dataclass
+from dataclasses import asdict, dataclass
 from datetime import timezone
 from enum import Enum
 from functools import partial, reduce
@@ -57,7 +57,7 @@
 from polars.testing import assert_frame_equal
 from typing_extensions import override
 
-from utilities.dataclasses import Dataclass, is_dataclass_class, yield_field_names
+from utilities.dataclasses import Dataclass, is_dataclass_class
 from utilities.errors import redirect_error
 from utilities.iterables import (
     CheckIterablesEqualError,
@@ -100,14 +100,15 @@
 
 def append_dataclass(df: DataFrame, obj: Dataclass, /) -> DataFrame:
     """Append a dataclass object to a DataFrame."""
-    fields = yield_field_names(obj)
+    non_null_fields = {k: v for k, v in asdict(obj).items() if v is not None}
     try:
-        check_subset(fields, df.columns)
+        check_subset(non_null_fields, df.columns)
     except CheckSubSetError as error:
         raise AppendDataClassError(
             left=error.left, right=error.right, extra=error.extra
         ) from None
-    row = dataclass_to_row(obj)
+    row_cols = set(df.columns) & set(non_null_fields)
+    row = dataclass_to_row(obj).select(*row_cols)
     return concat([df, row], how="diagonal")