diff --git a/app/services/post_alerter.rb b/app/services/post_alerter.rb
index ea1b8105903..ae560ec2fd9 100644
--- a/app/services/post_alerter.rb
+++ b/app/services/post_alerter.rb
@@ -280,7 +280,7 @@ class PostAlerter
 
     DiscourseEvent.trigger(:before_create_notification, user, type, post, opts)
 
-    return if user.blank? || user.bot?
+    return if user.blank? || user.bot? || post.blank?
     return if (topic = post.topic).blank?
 
     is_liked = type == Notification.types[:liked]