diff --git a/addons/mail/models/mail_activity.py b/addons/mail/models/mail_activity.py
index 770172340b4..42c44223a7c 100644
--- a/addons/mail/models/mail_activity.py
+++ b/addons/mail/models/mail_activity.py
@@ -140,7 +140,8 @@ class MailActivity(models.Model):
 
     @api.onchange('recommended_activity_type_id')
     def _onchange_recommended_activity_type_id(self):
-        self.activity_type_id = self.recommended_activity_type_id
+        if self.recommended_activity_type_id:
+            self.activity_type_id = self.recommended_activity_type_id
 
     @api.multi
     def _check_access(self, operation):