diff --git a/railties/lib/rails/rack/debugger.rb b/railties/lib/rails/rack/debugger.rb
index 06e23db5f1896..9e3423d189178 100644
--- a/railties/lib/rails/rack/debugger.rb
+++ b/railties/lib/rails/rack/debugger.rb
@@ -8,7 +8,7 @@ def initialize(app)
 
         ARGV.clear # clear ARGV so that rails server options aren't passed to IRB
 
-        require_library_or_gem 'ruby-debug'
+        require_library_or_gem(RUBY_VERSION < '1.9' ? 'ruby-debug' : 'ruby-debug19')
         ::Debugger.start
         ::Debugger.settings[:autoeval] = true if ::Debugger.respond_to?(:settings)
         puts "=> Debugger enabled"