diff --git a/omniauth.gemspec b/omniauth.gemspec
index 24c2afb..30d4f57 100644
--- a/omniauth.gemspec
+++ b/omniauth.gemspec
@@ -5,7 +5,7 @@ require 'omniauth/version'
 
 Gem::Specification.new do |spec|
   spec.add_dependency 'hashie', ['>= 1.2', '< 3']
-  spec.add_dependency 'rack'
+  spec.add_dependency 'rack', '~> 1.0'
   spec.add_development_dependency 'bundler', '~> 1.0'
   spec.authors       = ['Michael Bleigh', 'Erik Michaels-Ober']
   spec.cert_chain    = %w(certs/sferik.pem)