diff --git a/railties/railties.gemspec b/railties/railties.gemspec
index f1c92bd5d4dc9c348269d47bce5420587aea5fc4..9c535f4f9049dfd6db5f7903a486402edeea8afd 100644
--- a/railties/railties.gemspec
+++ b/railties/railties.gemspec
@@ -20,6 +20,7 @@
   s.add_dependency('rake',          '>= 0.8.7')
   s.add_dependency('thor',          '~> 0.14.6')
   s.add_dependency('rack-ssl',      '~> 1.3.2')
+  s.add_dependency('rdoc',          '~> 3.4')
   s.add_dependency('activesupport', version)
   s.add_dependency('actionpack',    version)
 end