diff --git a/addons/crm/crm_lead.py b/addons/crm/crm_lead.py
index f33d4c16ad5..0afac95535d 100644
--- a/addons/crm/crm_lead.py
+++ b/addons/crm/crm_lead.py
@@ -906,7 +906,7 @@ class crm_lead(format_address, osv.osv):
             vals.update(onchange_stage_values)
         if vals.get('probability') >= 100 or not vals.get('active', True):
             vals['date_closed'] = fields.datetime.now()
-        elif vals.get('probability') < 100:
+        elif 'probability' in vals and vals['probability'] < 100:
             vals['date_closed'] = False
         return super(crm_lead, self).write(cr, uid, ids, vals, context=context)