diff --git a/sncfgtfs/management/commands/update_sncf_gtfs.py b/sncfgtfs/management/commands/update_sncf_gtfs.py
index 4718f85..e801344 100644
--- a/sncfgtfs/management/commands/update_sncf_gtfs.py
+++ b/sncfgtfs/management/commands/update_sncf_gtfs.py
@@ -177,8 +177,7 @@ class Command(BaseCommand):
                             end_date=calendar_dict['end_date'],
                             transport_type=transport_type,
                         )
-                        calendars.append(calendar)
-                        calendar_ids.append(calendar.id)
+                        calendars[calendar.id] = calendar
 
                         if len(calendars) >= bulk_size and not dry_run:
                             Calendar.objects.bulk_create(calendars,