diff --git a/lib/couchrest_extended_document.rb b/lib/couchrest_extended_document.rb
index d256be4..2ac68cc 100644
--- a/lib/couchrest_extended_document.rb
+++ b/lib/couchrest_extended_document.rb
@@ -6,6 +6,7 @@ gem 'couchrest'
 require 'couchrest'
 
 require 'active_support/core_ext'
+require 'active_support/json'
 require 'mime/types'
 require "enumerator"