diff --git a/app/workflows/send_notification_for_comment_workflow.rb b/app/workflows/send_notification_for_comment_workflow.rb
index c81a0b59..045cdd9a 100644
--- a/app/workflows/send_notification_for_comment_workflow.rb
+++ b/app/workflows/send_notification_for_comment_workflow.rb
@@ -15,6 +15,8 @@ class SendNotificationForCommentWorkflow
     
     if comment.parent_id == nil # Reply to a post
       user = comment.post.user
+
+      return if user.nil? # anonymous posts don't have a user
       
       if comment.user.id != user.id and
         user.notifications_enabled? and