diff --git a/addons/base_calendar/base_calendar.py b/addons/base_calendar/base_calendar.py
index 5fef795acec..1c26e93b917 100644
--- a/addons/base_calendar/base_calendar.py
+++ b/addons/base_calendar/base_calendar.py
@@ -1028,8 +1028,8 @@ class calendar_event(osv.osv):
         'id': fields.integer('ID', readonly=True),
         'sequence': fields.integer('Sequence'),
         'name': fields.char('Description', size=64, required=False, states={'done': [('readonly', True)]}),
-        'date': fields.datetime('Date', required=True, states={'done': [('readonly', True)]}),
-        'date_deadline': fields.datetime('Deadline', required=True, states={'done': [('readonly', True)]}),
+        'date': fields.datetime('Date', states={'done': [('readonly', True)]}),
+        'date_deadline': fields.datetime('Deadline', states={'done': [('readonly', True)]}),
         'create_date': fields.datetime('Created', readonly=True),
         'duration': fields.float('Duration', states={'done': [('readonly', True)]}),
         'description': fields.text('Description', states={'done': [('readonly', True)]}),