diff --git a/management/commands/import_transaction.py b/management/commands/import_transaction.py
index 5c1192c..c29d5bd 100644
--- a/management/commands/import_transaction.py
+++ b/management/commands/import_transaction.py
@@ -214,7 +214,7 @@ class Command(ImportCommand):
                 "amount": row["montant"],
                 "created_at": date,
                 "destination_alias": "",
-                "invalidity_reason": None,
+                "invalidity_reason": "",
                 "quantity": row["quantite"],
                 "reason": row["description"],
                 "source_alias": "",