diff --git a/vagrant-mutate.gemspec b/vagrant-mutate.gemspec
index 562b50d..3d7f1a3 100644
--- a/vagrant-mutate.gemspec
+++ b/vagrant-mutate.gemspec
@@ -20,4 +20,5 @@ Gem::Specification.new do |spec|
 
   spec.add_development_dependency "bundler", "~> 1.3"
   spec.add_development_dependency "rake"
+  spec.add_runtime_dependency "nokogiri"
 end