diff --git a/app/preprocessing/transform_dataset.py b/app/preprocessing/transform_dataset.py
index 5711f94a9cc03e5a27b2767eede983db5acde0ee..914be5ad0cb0839ebcf8a132fbf960bf3ee4dd11 100644
--- a/app/preprocessing/transform_dataset.py
+++ b/app/preprocessing/transform_dataset.py
@@ -194,7 +194,7 @@ def _remove_unimportant_predictors(train_files: List[Path], all_files: List[Path
         df = pd.read_parquet(file)
 
         columns_to_drop = [col for col in df.columns if col not in columns_to_keep]
-        df.drop(columns=columns_to_drop)
+        df = df.drop(columns=columns_to_drop)
 
         df.to_parquet(out_dir / file.name)