diff --git a/addons/hr_timesheet/hr_timesheet.py b/addons/hr_timesheet/hr_timesheet.py
index 14e885a40a3..2faaf91cfd6 100644
--- a/addons/hr_timesheet/hr_timesheet.py
+++ b/addons/hr_timesheet/hr_timesheet.py
@@ -9,7 +9,7 @@ class AccountAnalyticLine(models.Model):
 
     task_id = fields.Many2one('project.task', 'Task')
     project_id = fields.Many2one('project.project', 'Project')
-    department_id = fields.Many2one('hr.department', "Department", related='user_id.employee_ids.department_id', store=True)
+    department_id = fields.Many2one('hr.department', "Department", related='user_id.employee_ids.department_id', store=True, readonly=True)
 
     @api.onchange('project_id')
     def onchange_project_id(self):