diff --git a/lib/v8/context.rb b/lib/v8/context.rb
index 90d50b4..cf01b4a 100644
--- a/lib/v8/context.rb
+++ b/lib/v8/context.rb
@@ -1,3 +1,4 @@
+require 'stringio'
 module V8
   class Context
     attr_reader :native, :conversion, :access