1 files changed, 2 insertions, 4 deletions
diff --git a/actionpack/lib/action_controller/metal.rb b/actionpack/lib/action_controller/metal.rb
index 696fbf6e09..3bfc8d6460 100644
--- a/actionpack/lib/action_controller/metal.rb
+++ b/actionpack/lib/action_controller/metal.rb
@@ -30,10 +30,8 @@ module ActionController
       end
     end
 
-    def build(action, app=nil, &block)
-      app  ||= block
+    def build(action, app = Proc.new)
       action = action.to_s
-      raise "MiddlewareStack#build requires an app" unless app
 
       middlewares.reverse.inject(app) do |a, middleware|
         middleware.valid?(action) ? middleware.build(a) : a
@@ -228,7 +226,7 @@ module ActionController
 
     # Returns a Rack endpoint for the given action name.
     def self.action(name, klass = ActionDispatch::Request)
-      middleware_stack.build(name.to_s) do |env|
+      middleware_stack.build(name) do |env|
         new.dispatch(name, klass.new(env))
       end
     end