diff --git a/src/Dataset.py b/src/Dataset.py
index 72cb721bc4450a5a21a3a99f195ec3819c670188..312a6e249651d85363674bdff328599cc83bd3ef 100644
--- a/src/Dataset.py
+++ b/src/Dataset.py
@@ -122,7 +122,7 @@ class Dataset:
         is_competitive_col = self.get_is_competitive_col(dataframe)
         return is_competitive_col
 
-    def treat_outliers(self, df, colname):
+    def treat_outliers(self, df, colname) -> pd.DataFrame:
         q = df[colname].quantile(0.99)
         return df[df[colname] < q]