diff --git a/addons/crm/wizard/crm_lead_to_opportunity.py b/addons/crm/wizard/crm_lead_to_opportunity.py
index 2d7b8b77489..e56dd0583d0 100644
--- a/addons/crm/wizard/crm_lead_to_opportunity.py
+++ b/addons/crm/wizard/crm_lead_to_opportunity.py
@@ -126,7 +126,7 @@ class Lead2OpportunityPartner(models.TransientModel):
         to_merge = self.duplicated_lead_ids
         result_opportunity = to_merge.merge_opportunity(auto_unlink=False)
         if not result_opportunity.active:
-            result_opportunity.write({'active': True, 'activity_type_id': False, 'lost_reason': False})
+            result_opportunity.write({'active': True, 'lost_reason': False})
 
         if result_opportunity.type == "lead":
             self._convert_and_allocate(result_opportunity, [self.user_id.id], team_id=self.team_id.id)