diff --git a/app/controllers/application_controller.rb b/app/controllers/application_controller.rb
index 9c0beedf85a..65d688e4135 100644
--- a/app/controllers/application_controller.rb
+++ b/app/controllers/application_controller.rb
@@ -14,6 +14,7 @@ require_dependency 'global_path'
 require_dependency 'secure_session'
 require_dependency 'topic_query'
 require_dependency 'hijack'
+require_dependency 'read_only'
 
 class ApplicationController < ActionController::Base
   include CurrentUser
@@ -21,6 +22,7 @@ class ApplicationController < ActionController::Base
   include JsonError
   include GlobalPath
   include Hijack
+  include ReadOnly
 
   attr_reader :theme_ids
 
@@ -80,10 +82,6 @@ class ApplicationController < ActionController::Base
       (has_escaped_fragment? || CrawlerDetection.crawler?(request.user_agent) || params.key?("print"))
   end
 
-  def add_readonly_header
-    response.headers['Discourse-Readonly'] = 'true' if @readonly_mode
-  end
-
   def perform_refresh_session
     refresh_session(current_user) unless @readonly_mode
   end
@@ -508,10 +506,6 @@ class ApplicationController < ActionController::Base
 
   private
 
-  def check_readonly_mode
-    @readonly_mode = Discourse.readonly_mode?
-  end
-
   def locale_from_header
     begin
       # Rails I18n uses underscores between the locale and the region; the request
diff --git a/app/controllers/forums_controller.rb b/app/controllers/forums_controller.rb
index 7071a04ec38..b3b0a749924 100644
--- a/app/controllers/forums_controller.rb
+++ b/app/controllers/forums_controller.rb
@@ -1,6 +1,13 @@
 # frozen_string_literal: true
 
+require "read_only"
+
 class ForumsController < ActionController::Base
+  include ReadOnly
+
+  before_action :check_readonly_mode
+  after_action  :add_readonly_header
+
   def status
     if $shutdown
       render plain: 'shutting down', status: 500
diff --git a/lib/read_only.rb b/lib/read_only.rb
new file mode 100644
index 00000000000..d095d18ad85
--- /dev/null
+++ b/lib/read_only.rb
@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+module ReadOnly
+
+  def check_readonly_mode
+    @readonly_mode = Discourse.readonly_mode?
+  end
+
+  def add_readonly_header
+    response.headers['Discourse-Readonly'] = 'true' if @readonly_mode
+  end
+
+end
diff --git a/spec/requests/forums_controller_spec.rb b/spec/requests/forums_controller_spec.rb
new file mode 100644
index 00000000000..c288909dd60
--- /dev/null
+++ b/spec/requests/forums_controller_spec.rb
@@ -0,0 +1,22 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe ForumsController do
+
+  describe "read only header" do
+    it "returns no read only header by default" do
+      get "/srv/status"
+      expect(response.status).to eq(200)
+      expect(response.headers['Discourse-Readonly']).to eq(nil)
+    end
+
+    it "returns a readonly header if the site is read only" do
+      Discourse.received_readonly!
+      get "/srv/status"
+      expect(response.status).to eq(200)
+      expect(response.headers['Discourse-Readonly']).to eq('true')
+    end
+  end
+
+end