diff --git a/README.md b/README.md
index b9df136..d1cac04 100644
--- a/README.md
+++ b/README.md
@@ -29,7 +29,7 @@ defmodule MyApp.Book do
   use MyApp.Web, :model
 
   schema "books" do
-    field :isbn, ISN.ISBN13
+    field :isbn, ISN.ISBN13, read_after_writes: true
     # other fields
   end
 end
@@ -49,11 +49,19 @@ end
 
     mix do isn.gen.migration, ecto.migrate
 
-**Register the postgrex extension in your Repo config**
+**In lib/ directory create a file with the following content:**
 ```elixir
-config :books, MyApp.Repo,
-  adapter: Ecto.Adapters.Postgres,
-  extensions: [{ISN, []}]
+Postgrex.Types.define(
+  MyApp.PostgrexTypes,
+  [ISN] ++ Ecto.Adapters.Postgres.extensions(),
+  json: Poison
+)
+```
+
+**Add the following lines in conig.exs:**
+```elixir
+config :my_app, MyApp.Repo,
+  types: MyApp.PostgrexTypes
 ```
 
 ## Defined types
@@ -75,4 +83,4 @@ Ecto.Type    | Postgrex type
 [2]: http://hexdocs.pm/ecto/Ecto.Type.html
 [3]: http://www.postgresql.org/docs/9.4/static/isn.html
 [4]: https://semaphoreci.com/api/v1/projects/be7c4c34-c49e-45c7-9320-3fcc4f7f476a/458429/badge.svg
-[5]: https://semaphoreci.com/frost/isn
\ No newline at end of file
+[5]: https://semaphoreci.com/frost/isn
diff --git a/lib/isn.ex b/lib/isn.ex
index bfbd0e0..c7b8358 100644
--- a/lib/isn.ex
+++ b/lib/isn.ex
@@ -6,7 +6,7 @@ defmodule ISN do
   A Postgrex.Extension enabling the use of postgresql data types from the isn
   extension.
 
-  In lib/ directory create a file called postgrex_types.ex with the following content:
+  In lib/ directory create a file with the following content:
 
     Postgrex.Types.define(
       MyApp.PostgrexTypes,