diff --git a/crates/polars-io/src/csv/read/reader.rs b/crates/polars-io/src/csv/read/reader.rs
index 88a3fe6786f8..fb056bec96f9 100644
--- a/crates/polars-io/src/csv/read/reader.rs
+++ b/crates/polars-io/src/csv/read/reader.rs
@@ -165,7 +165,7 @@ impl<R: MmapBytesReader> CsvReader<R> {
         let mut process_schema = |schema: &Schema| {
             schema
                 .iter_fields()
-                .filter_map(|mut fld| {
+                .map(|mut fld| {
                     use DataType::*;
 
                     match fld.data_type() {
@@ -173,25 +173,25 @@ impl<R: MmapBytesReader> CsvReader<R> {
                             self.options.fields_to_cast.push(fld.clone());
                             // let inference decide the column type
                             fld.coerce(String);
-                            Some(Ok(fld))
+                            Ok(fld)
                         },
                         #[cfg(feature = "dtype-categorical")]
                         Categorical(_, _) => {
                             _has_categorical = true;
-                            Some(Ok(fld))
+                            Ok(fld)
                         },
                         #[cfg(feature = "dtype-decimal")]
                         Decimal(precision, scale) => match (precision, scale) {
                             (_, Some(_)) => {
                                 self.options.fields_to_cast.push(fld.clone());
                                 fld.coerce(String);
-                                Some(Ok(fld))
+                                Ok(fld)
                             },
-                            _ => Some(Err(PolarsError::ComputeError(
+                            _ => Err(PolarsError::ComputeError(
                                 "'scale' must be set when reading csv column as Decimal".into(),
-                            ))),
+                            )),
                         },
-                        _ => Some(Ok(fld)),
+                        _ => Ok(fld),
                     }
                 })
                 .collect::<PolarsResult<Schema>>()
diff --git a/py-polars/tests/unit/io/test_csv.py b/py-polars/tests/unit/io/test_csv.py
index d352a7d8fd5a..10a52e50acd9 100644
--- a/py-polars/tests/unit/io/test_csv.py
+++ b/py-polars/tests/unit/io/test_csv.py
@@ -2253,6 +2253,7 @@ def test_write_csv_raise_on_non_utf8_17328(
     with pytest.raises(InvalidOperationError, match="file encoding is not UTF-8"):
         df_no_lists.write_csv((tmp_path / "dangling.csv").open("w", encoding="gbk"))
 
+
 @pytest.mark.write_disk()
 def test_write_csv_appending_17543(tmp_path: Path) -> None:
     tmp_path.mkdir(exist_ok=True)
@@ -2264,6 +2265,7 @@ def test_write_csv_appending_17543(tmp_path: Path) -> None:
         assert f.readline() == "# test\n"
         assert pl.read_csv(f).equals(df)
 
+
 @pytest.mark.parametrize(
     ("dtype", "df"),
     [
@@ -2273,19 +2275,15 @@ def test_write_csv_appending_17543(tmp_path: Path) -> None:
             pl.Time,
             pl.DataFrame({"x": ["12:15:00"]}).with_columns(
                 pl.col("x").str.strptime(pl.Time)
-            )
+            ),
         ),
-    ]
+    ],
 )
 def test_read_csv_cast_unparsable_later(
-    tmp_path: Path,
-    dtype: pl.Decimal | pl.Categorical | pl.Time,
-    df: pl.DataFrame
+    tmp_path: Path, dtype: pl.Decimal | pl.Categorical | pl.Time, df: pl.DataFrame
 ) -> None:
     tmp_path.mkdir(exist_ok=True)
     with (tmp_path / "append.csv").open("w") as f:
         df.write_csv(f)
     with (tmp_path / "append.csv").open("r") as f:
-        assert df.equals(
-            pl.read_csv(f, schema={"x": dtype})
-        )
+        assert df.equals(pl.read_csv(f, schema={"x": dtype}))