diff --git a/app/controllers/topics_controller.rb b/app/controllers/topics_controller.rb
index fa778fda331..33885ab8f07 100644
--- a/app/controllers/topics_controller.rb
+++ b/app/controllers/topics_controller.rb
@@ -840,6 +840,8 @@ class TopicsController < ApplicationController
   end
 
   def feed
+    raise Discourse::NotFound if !Post.exists?(topic_id: params[:topic_id])
+
     @topic_view = TopicView.new(params[:topic_id])
     discourse_expires_in 1.minute
     render 'topics/show', formats: [:rss]
diff --git a/spec/requests/topics_controller_spec.rb b/spec/requests/topics_controller_spec.rb
index ac18ce3550b..5419e2fb049 100644
--- a/spec/requests/topics_controller_spec.rb
+++ b/spec/requests/topics_controller_spec.rb
@@ -2519,6 +2519,12 @@ RSpec.describe TopicsController do
       expect(response.body).to_not include("/forum/forum")
       expect(response.body).to include("http://test.localhost/forum/t/#{topic.slug}")
     end
+
+    it 'returns 404 when posts are deleted' do
+      topic.posts.each(&:trash!)
+      get "/t/foo/#{topic.id}.rss"
+      expect(response.status).to eq(404)
+    end
   end
 
   describe '#invite_group' do