1 files changed, 6 insertions, 5 deletions
diff --git a/actionpack/lib/action_controller/base.rb b/actionpack/lib/action_controller/base.rb
index 9941c06201..a00eafc9ed 100644
--- a/actionpack/lib/action_controller/base.rb
+++ b/actionpack/lib/action_controller/base.rb
@@ -261,11 +261,12 @@ module ActionController
       include mod
     end
 
-    # Define some internal variables that should not be propagated to the view.
-    self.protected_instance_variables = [
-      :@_status, :@_headers, :@_params, :@_env, :@_response, :@_request,
-      :@_view_runtime, :@_stream, :@_url_options, :@_action_has_layout
-    ]
+    def self.default_protected_instance_vars
+      super.concat [
+        :@_status, :@_headers, :@_params, :@_env, :@_response, :@_request,
+        :@_view_runtime, :@_stream, :@_url_options, :@_action_has_layout
+      ]
+    end
 
     ActiveSupport.run_load_hooks(:action_controller, self)
   end