diff --git a/Gemfile b/Gemfile
index 39604cb..9a39411 100644
--- a/Gemfile
+++ b/Gemfile
@@ -5,3 +5,7 @@
   gem 'rspec', '~> 3.1.0'
   gem 'webmock', '~> 1.20.4'
 end
+
+group :doc do
+  gem 'rdoc', '~> 4.2.0'
+end
\ No newline at end of file
diff --git a/predictionio.gemspec b/predictionio.gemspec
index 535594f..cbfd196 100644
--- a/predictionio.gemspec
+++ b/predictionio.gemspec
@@ -1,3 +1,6 @@
+$:.push File.expand_path('../lib', __FILE__)
+require 'predictionio/version'
+
 Gem::Specification.new do |s|
   s.name = 'predictionio'
   s.summary = 'PredictionIO Ruby SDK'