diff --git a/oauth2.gemspec b/oauth2.gemspec
index ba68f68b..0edfb167 100644
--- a/oauth2.gemspec
+++ b/oauth2.gemspec
@@ -6,6 +6,7 @@ Gem::Specification.new do |gem|
   gem.add_dependency 'httpauth', '~> 0.1'
   gem.add_dependency 'multi_json', '~> 1.3'
   gem.add_dependency 'rack', '~> 1.4'
+  gem.add_development_dependency 'addressable'
   gem.add_development_dependency 'multi_xml'
   gem.add_development_dependency 'rake'
   gem.add_development_dependency 'rdoc'
diff --git a/spec/helper.rb b/spec/helper.rb
index d2118d51..8dda3299 100644
--- a/spec/helper.rb
+++ b/spec/helper.rb
@@ -3,6 +3,7 @@
   SimpleCov.start
 end
 require 'oauth2'
+require 'addressable/uri'
 require 'rspec'
 require 'rspec/autorun'