diff --git a/railties/lib/rails/application.rb b/railties/lib/rails/application.rb
index 8b8ef20b1f..eca6802297 100644
--- a/railties/lib/rails/application.rb
+++ b/railties/lib/rails/application.rb
@@ -160,6 +160,7 @@ module Rails
         config.middleware.build(routes)
       end
     end
+    alias :build_middleware_stack :app
 
     def call(env)
       app.call(env.reverse_merge!(env_defaults))
diff --git a/railties/lib/rails/application/finisher.rb b/railties/lib/rails/application/finisher.rb
index d7ff489336..11a3329de6 100644
--- a/railties/lib/rails/application/finisher.rb
+++ b/railties/lib/rails/application/finisher.rb
@@ -32,7 +32,7 @@ module Rails
       end
 
       initializer :build_middleware_stack do
-        app
+        build_middleware_stack
       end
 
       initializer :eager_load! do