diff --git a/py-polars/src/dataframe.rs b/py-polars/src/dataframe.rs
index 8f95587ef9154..3d96c4437b984 100644
--- a/py-polars/src/dataframe.rs
+++ b/py-polars/src/dataframe.rs
@@ -51,26 +51,30 @@ impl PyDataFrame {
         rows: Vec<Row>,
         infer_schema_length: Option<usize>,
         schema: Option<Schema>,
-        schema_overrides_by_idx: Option<PlHashMap<usize, DataType>>,
+        schema_overrides_by_idx: Option<Vec<(usize, DataType)>>,
     ) -> PyResult<Self> {
         // Object builder must be registered, this is done on import.
-        let s = rows_to_schema_supertypes(&rows, infer_schema_length.map(|n| std::cmp::max(1, n)))
-            .map_err(PyPolarsErr::from)?;
+        let inferred_schema =
+            rows_to_schema_supertypes(&rows, infer_schema_length.map(|n| std::cmp::max(1, n)))
+                .map_err(PyPolarsErr::from)?;
 
         // Replace inferred nulls with boolean and erase scale from inferred decimals.
-        let fields = s.iter_fields().map(|mut fld| match fld.data_type() {
-            DataType::Null => {
-                fld.coerce(DataType::Boolean);
-                fld
-            },
-            DataType::Decimal(_, _) => {
-                fld.coerce(DataType::Decimal(None, None));
-                fld
-            },
-            _ => fld,
-        });
-
-        let mut final_schema = Schema::from_iter(fields);
+        let mut final_schema =
+            Schema::from_iter(
+                inferred_schema
+                    .iter_fields()
+                    .map(|mut fld| match fld.data_type() {
+                        DataType::Null => {
+                            fld.coerce(DataType::Boolean);
+                            fld
+                        },
+                        DataType::Decimal(_, _) => {
+                            fld.coerce(DataType::Decimal(None, None));
+                            fld
+                        },
+                        _ => fld,
+                    }),
+            );
         if let Some(schema) = schema {
             for (i, (name, dtype)) in schema.into_iter().enumerate() {
                 if let Some((name_, dtype_)) = final_schema.get_at_index_mut(i) {
@@ -543,12 +547,11 @@ impl PyDataFrame {
             schema_columns.extend(s.0.iter_names().map(|n| n.to_string()))
         }
         let (rows, names) = dicts_to_rows(dicts, infer_schema_length, schema_columns)?;
-
-        let mut schema_overrides_by_idx: PlHashMap<usize, DataType> = PlHashMap::new();
+        let mut schema_overrides_by_idx: Vec<(usize, DataType)> = Vec::new();
         if let Some(overrides) = schema_overrides {
             for (idx, name) in names.iter().enumerate() {
                 if let Some(dtype) = overrides.0.get(name) {
-                    schema_overrides_by_idx.insert(idx, dtype.clone());
+                    schema_overrides_by_idx.push((idx, dtype.clone()));
                 }
             }
         }