diff --git a/activesupport/lib/active_support/orchestra.rb b/activesupport/lib/active_support/orchestra.rb
index 7d4c25669d3dd85afdaf443f2a330b16c1b60fc4..96e6ce886534a8c77bc9507c50ebef8775607800 100644
--- a/activesupport/lib/active_support/orchestra.rb
+++ b/activesupport/lib/active_support/orchestra.rb
@@ -1,5 +1,6 @@
 require 'thread'
 require 'active_support/core_ext/module/delegation'
+require 'active_support/core_ext/module/attribute_accessors'
 
 module ActiveSupport
   # Orchestra provides an instrumentation API for Ruby. To instrument an action
diff --git a/railties/test/application/orchestra_test.rb b/railties/test/application/orchestra_test.rb
index 38a06be741de3995321d9e15bf579f2ee9868af7..fcf073bd6fda04002c70fdf06ef0d994209286e0 100644
--- a/railties/test/application/orchestra_test.rb
+++ b/railties/test/application/orchestra_test.rb
@@ -1,8 +1,8 @@
 require "isolation/abstract_unit"
-require "active_support/orchestra"
 
 module ApplicationTests
   class OrchestraTest < Test::Unit::TestCase
+    include ActiveSupport::Testing::Isolation
 
     class MyQueue
       attr_reader :events, :subscribers
@@ -25,6 +25,7 @@ def setup
       build_app
       boot_rails
 
+      require "active_support/orchestra"
       Rails::Initializer.run do |c|
         c.orchestra.queue = MyQueue.new
         c.orchestra.subscribe(/listening/) do