diff --git a/resource_work_time_from_contracts/models/resource_mixin.py b/resource_work_time_from_contracts/models/resource_mixin.py
index 442869f61..42f6fc3cb 100644
--- a/resource_work_time_from_contracts/models/resource_mixin.py
+++ b/resource_work_time_from_contracts/models/resource_mixin.py
@@ -16,8 +16,7 @@ class ResourceMixin(models.AbstractModel):
 
     _inherit = "resource.mixin"
 
-    # make this field read-only.
-    resource_calendar_id = fields.Many2one("resource.calendar", readonly=True)
+    resource_calendar_id = fields.Many2one("resource.calendar")
 
     def list_work_time_per_day(
         self,