diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..b844b14
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+Gemfile.lock
diff --git a/Gemfile b/Gemfile
new file mode 100644
index 0000000..0f6f77f
--- /dev/null
+++ b/Gemfile
@@ -0,0 +1,9 @@
+source :rubygems
+
+gemspec
+
+group :test do
+  gem 'mustang',      :platform => :ruby
+  gem 'therubyracer', :platform => :ruby
+  gem 'therubyrhino', :platform => :jruby
+end
diff --git a/execjs.gemspec b/execjs.gemspec
index bfcb57e..9c15482 100644
--- a/execjs.gemspec
+++ b/execjs.gemspec
@@ -27,9 +27,7 @@ Gem::Specification.new do |s|
   ]
 
   s.add_dependency "multi_json", "~>1.0"
-  s.add_development_dependency "mustang"
-  s.add_development_dependency "therubyracer"
-  s.add_development_dependency "therubyrhino"
+  s.add_development_dependency "rake"
 
   s.authors           = ["Sam Stephenson", "Josh Peek"]
   s.email             = ["sstephenson@gmail.com", "josh@joshpeek.com"]