diff --git a/prototype-rails.gemspec b/prototype-rails.gemspec
index 665b1f1..8837978 100644
--- a/prototype-rails.gemspec
+++ b/prototype-rails.gemspec
@@ -8,7 +8,7 @@ Gem::Specification.new do |spec|
 
   spec.files = %w(README.md Rakefile Gemfile MIT-LICENSE) + Dir['lib/**/*', 'vendor/**/*', 'test/**/*']
 
-  spec.add_dependency('rails', '~> 4.0')
+  spec.add_dependency('rails')
   spec.add_development_dependency('mocha')
   spec.license = "MIT"
 end