diff --git a/lib/oga.rb b/lib/oga.rb
index c0d9776..75cf725 100644
--- a/lib/oga.rb
+++ b/lib/oga.rb
@@ -1,3 +1,5 @@
+gem 'racc'
+
 require 'ast'
 require 'set'
 require 'stringio'