diff --git a/lib/isn.ex b/lib/isn.ex
index 007453e..a83f6d9 100644
--- a/lib/isn.ex
+++ b/lib/isn.ex
@@ -42,7 +42,7 @@ defmodule Isn do
   def init(parameters, _opts),
     do: parameters
 
-  def matching(_library),
+  def matching(_),
     do: Enum.zip(Stream.cycle([:type]), @isn)
 
   def format(_),
@@ -81,8 +81,6 @@ for module <- ~w(ISBN ISMN ISSN ISBN13 ISMN13 ISSN13 UPC EAN13) do
 
     def type, do: unquote(ecto_type)
 
-    defdelegate blank?, to: Ecto.Type
-
     def cast(nil), do: :error
     def cast(isn), do: {:ok, to_string(isn)}