diff --git a/sncfgtfs/management/commands/update_sncf_gtfs.py b/sncfgtfs/management/commands/update_sncf_gtfs.py
index ddb7372..dee97d7 100644
--- a/sncfgtfs/management/commands/update_sncf_gtfs.py
+++ b/sncfgtfs/management/commands/update_sncf_gtfs.py
@@ -180,7 +180,7 @@ class Command(BaseCommand):
                         calendars[calendar.id] = calendar
 
                         if len(calendars) >= bulk_size and not dry_run:
-                            Calendar.objects.bulk_create(calendars,
+                            Calendar.objects.bulk_create(calendars.values(),
                                                          update_conflicts=True,
                                                          update_fields=['monday', 'tuesday', 'wednesday', 'thursday',
                                                                         'friday', 'saturday', 'sunday', 'start_date',