diff --git a/letter_opener_web.gemspec b/letter_opener_web.gemspec
index 51d4e55..83a884d 100644
--- a/letter_opener_web.gemspec
+++ b/letter_opener_web.gemspec
@@ -18,7 +18,8 @@ Gem::Specification.new do |gem|
   gem.test_files    = gem.files.grep(%r{^(test|spec|features)/})
   gem.require_paths = ["lib"]
 
-  gem.add_dependency 'rails', '>= 3.2'
+  gem.add_dependency 'railties', '>= 3.2'
+  gem.add_dependency 'action_mailer', '>= 3.2'
   gem.add_dependency 'letter_opener', '~> 1.0'
 
   gem.add_development_dependency 'rspec-rails', '~> 3.0'