diff --git a/Gemfile b/Gemfile
index f011ab83ea..61c6d2785a 100644
--- a/Gemfile
+++ b/Gemfile
@@ -5,6 +5,7 @@ gemspec
 group :development do
   gem "benchmark-driver"
   gem "rake-compiler"
+  gem "rdoc"
   gem "ruby-maven", :platforms => :jruby
   gem "test-unit"
   gem "test-unit-ruby-core"