diff --git a/Rakefile b/Rakefile
index 69f18bb7..5a0920c7 100644
--- a/Rakefile
+++ b/Rakefile
@@ -23,11 +23,11 @@ task :default => :spec
 desc "Generate RDoc"
 task :docs do
   FileUtils.rm_rf("doc")
-  require "rack/test"
-  system "hanna --title 'Rack::Test #{Rack::Test::VERSION} API Documentation'"
+  require "rack/test/version"
+  sh "rdoc --title 'Rack::Test #{Rack::Test::VERSION} API Documentation'"
 end
 
 desc 'Removes trailing whitespace'
 task :whitespace do
-  sh %{find . -name '*.rb' -exec sed -i '' 's/ *$//g' {} \\;}
+  sh %{find . -name '*.rb' -exec sed -i 's/ *$//g' {} \\;}
 end
diff --git a/rack-test.gemspec b/rack-test.gemspec
index 8d0d76ac..e43ef0f1 100644
--- a/rack-test.gemspec
+++ b/rack-test.gemspec
@@ -25,6 +25,7 @@ request helpers feature.
   s.add_development_dependency 'rake', '~> 12.0'
   s.add_development_dependency 'rspec', '~> 3.6'
   s.add_development_dependency 'sinatra', '>= 1.0', '< 3'
+  s.add_development_dependency 'rdoc', '~> 5.1'
   # Keep version < 1 to supress deprecated warning temporary.
   s.add_development_dependency 'codeclimate-test-reporter', '~> 0.6'
   # For Thorfile. Run "bundle exec thor help" to see the help.