diff --git a/config/config.exs b/config/config.exs
index f99d2fa..27a6afa 100644
--- a/config/config.exs
+++ b/config/config.exs
@@ -25,4 +25,3 @@ use Mix.Config
 #
 #     import_config "#{Mix.env}.exs"
 
-config :ex_doc, :markdown_processor, ExDoc.Markdown.Pandoc
diff --git a/config/dev.exs b/config/dev.exs
new file mode 100644
index 0000000..def509a
--- /dev/null
+++ b/config/dev.exs
@@ -0,0 +1,3 @@
+use Mix.Config
+
+config :ex_doc, :markdown_processor, ExDoc.Markdown.Pandoc
diff --git a/lib/isn.ex b/lib/isn.ex
index 0b7d5c2..574691b 100644
--- a/lib/isn.ex
+++ b/lib/isn.ex
@@ -1,6 +1,4 @@
 defmodule ISN do
-  alias Postgrex.TypeInfo
-
   @behaviour Postgrex.Extension
   @isn ~w(ean13 isbn13 ismn13 issn13 isbn ismn issn upc)
 
@@ -47,7 +45,7 @@ defmodule ISN do
   def format(_),
     do: :text
 
-  def encode(opts) do
+  def encode(_opts) do
     quote do
       thing ->
         [<<IO.iodata_length(thing) :: int32>> | thing]