diff --git a/marketing_automation.py b/marketing_automation.py
index 5bda7670d4..6d92b1dec4 100644
--- a/marketing_automation.py
+++ b/marketing_automation.py
@@ -303,7 +303,7 @@ class Activity(ModelSQL, ModelView):
 
     delay = fields.TimeDelta(
         "Delay",
-        domain=[
+        domain=['OR',
             ('delay', '=', None),
             ('delay', '>=', TimeDelta()),
             ],