diff --git a/addons/calendar/models/calendar.py b/addons/calendar/models/calendar.py
index 793fd1055f7..34f0b86b3fb 100644
--- a/addons/calendar/models/calendar.py
+++ b/addons/calendar/models/calendar.py
@@ -1415,7 +1415,7 @@ class Meeting(models.Model):
                     partners_to_notify = meeting.partner_ids.ids
                     event_attendees_changes = attendees_create and real_ids and attendees_create[real_ids[0]]
                     if event_attendees_changes:
-                        partners_to_notify.append(event_attendees_changes['removed_partners'].ids)
+                        partners_to_notify.extend(event_attendees_changes['removed_partners'].ids)
                     self.env['calendar.alarm_manager'].notify_next_alarm(partners_to_notify)
 
             if (values.get('start_date') or values.get('start_datetime') or