diff --git a/flash/data/data_utils.py b/flash/data/data_utils.py
index 0529884b34..50e6b3bf63 100644
--- a/flash/data/data_utils.py
+++ b/flash/data/data_utils.py
@@ -3,7 +3,7 @@
 import pandas as pd
 
 
-def labels_from_categorical_csv(csv: str, index_col: str, return_dict: dict = True) -> Union[Dict, List]:
+def labels_from_categorical_csv(csv: str, index_col: str, return_dict: bool = True) -> Union[Dict, List]:
     """
     Returns a dictionary with {index_col: label} for each entry in the csv.