diff --git a/README.md b/README.md
index 4727b2db..d9685050 100644
--- a/README.md
+++ b/README.md
@@ -26,7 +26,7 @@ and
 class CommentSerializer < ActiveModel::Serializer
   attribute :name, :body
   
-  belongs_to :post_id
+  belongs_to :post
   
   url [:post, :comment]
 end