diff --git a/pusher.gemspec b/pusher.gemspec
index 2182c8b..e46fb09 100644
--- a/pusher.gemspec
+++ b/pusher.gemspec
@@ -21,6 +21,7 @@ Gem::Specification.new do |s|
   s.add_development_dependency "rspec", "~> 3.0"
   s.add_development_dependency "webmock"
   s.add_development_dependency "em-http-request", "~> 1.1.0"
+  s.add_development_dependency "addressable", "=2.4.0"
   s.add_development_dependency "rake", "~> 10.4.2"
   s.add_development_dependency "rack", "~> 1.6.4"
   s.add_development_dependency "json", "~> 1.8.3"