diff --git a/addons/event_project/event.py b/addons/event_project/event.py
index 2a4733db73f..6f5a5ee6a9c 100644
--- a/addons/event_project/event.py
+++ b/addons/event_project/event.py
@@ -51,6 +51,7 @@ class event(osv.osv):
     def write(self, cr, uid, ids,vals, *args, **kwargs):
         if 'date_begin' in vals and vals['date_begin']:
             for eve in self.browse(cr, uid, ids):
+                if eve.project_id:
                     self.pool.get('project.project').write(cr, uid, [eve.project_id.id], {'date_end':eve.date_begin[:10]})
 
         return super(event,self).write(cr, uid, ids,vals, *args, **kwargs)