diff --git a/Rakefile b/Rakefile
index 3a44cb0..0a08f0d 100644
--- a/Rakefile
+++ b/Rakefile
@@ -1,6 +1,9 @@
 require "bundler/gem_tasks"
 require "rake/testtask"
 
+CLEAN.add("{ext,lib}/**/*.{o,so,bundle}", "pkg")
+CLOBBER.add("Gemfile.lock")
+
 Rake::TestTask.new(:test) do |t|
   t.libs << "test"
   t.libs << "lib"
@@ -26,7 +29,6 @@ else
 end
 
 
-
 # via http://blog.flavorjon.es/2009/06/easily-valgrind-gdb-your-ruby-c.html
 namespace :test do
   desc "run test suite with Address Sanitizer"
diff --git a/mini_racer.gemspec b/mini_racer.gemspec
index 1eeaee2..e87bd08 100644
--- a/mini_racer.gemspec
+++ b/mini_racer.gemspec
@@ -21,7 +21,7 @@ Gem::Specification.new do |spec|
     "source_code_uri"   => "https://github.com/discourse/mini_racer/tree/v#{spec.version}",
   }
 
-  spec.files         = Dir["lib/**/*", "ext/**/*", "README.md", "LICENSE.txt", "CHANGELOG", "CODE_OF_CONDUCT.md"]
+  spec.files         = Dir["lib/**/*.rb", "ext/**/*", "README.md", "LICENSE.txt", "CHANGELOG", "CODE_OF_CONDUCT.md"]
   spec.require_paths = ["lib"]
 
   spec.add_development_dependency "bundler"