diff --git a/test/request_test.rb b/test/request_test.rb
index c61a60cb..784dc975 100644
--- a/test/request_test.rb
+++ b/test/request_test.rb
@@ -1,4 +1,5 @@
 require File.dirname(__FILE__) + '/helper'
+require 'stringio'
 
 class RequestTest < Test::Unit::TestCase
   it 'responds to #user_agent' do