No need to handle nil header values.

README.md

@@ -15,7 +15,10 @@ defp deps do
 end
 ```
 
-Add the plug to e.g. a pipeline in a [Phoenix](http://www.phoenixframework.org/) controller. In this case we will require the request header `x-api-key` to be set, extract its first value and assign it the connection (a `Plug.Conn`) for later use in another plug or action.
+Add the plug to e.g. a pipeline in a [Phoenix](http://www.phoenixframework.org/)
+controller. In this case we will require the request header `x-api-key` to be set,
+extract its first value and assign it the connection (a `Plug.Conn`) for later use
+in another plug or action.
 ```elixir
 defmodule MyPhoenixApp.MyController do
   use MyPhoenixApp.Web, :controller
@@ -31,9 +34,14 @@ defmodule MyPhoenixApp.MyController do
   end
 end
 ```
-Notice how the first value required header `"x-api-key"` has been extracted and can be retrieved using `conn.assigns[:api_key]`. An alternative is to use `Plug.Conn.get_req_header/2` to get all the values associated with a given header.
+Notice how the first value required header `"x-api-key"` has been extracted
+and can be retrieved using `conn.assigns[:api_key]`. An alternative is to use
+`Plug.Conn.get_req_header/2` to get all the values associated with a given header.
 
-By default, a missing header will return a status code of 403 (forbidden) and halt the plug pipeline, i.e. no subsequent plugs will be executed. The same is true if the required header is explicitly set to `nil`. This behaviour however is configurable.
+By default, a missing header will return a status code of 403 (forbidden) and halt
+the plug pipeline, i.e. no subsequent plugs will be executed. The same is true if
+the required header is explicitly set to `nil` as the underlying HTTP server will
+not include the header. This behaviour however is configurable.
 ```elixir
 defmodule MyPhoenixApp.MyOtherController do
   use MyPhoenixApp.Web, :controller
@@ -55,7 +63,10 @@ defmodule MyPhoenixApp.MyOtherController do
   end
 end
 ```
-If the header is missing or set to `nil` the status code, a status code of 400 (bad request) will be returned before the plug pipeline is halted. Notice that the function specified as a callback needs to be a public function as it'll be invoked from another module.
+If the header is missing or set to `nil` the status code, a status code of 400
+(bad request) will be returned before the plug pipeline is halted. Notice that
+the function specified as a callback needs to be a public function as it'll be
+invoked from another module.
 
 Lastly, it's possible to extract multiple headers at the same time.
 

lib/plug_require_header.ex

@@ -2,7 +2,7 @@ defmodule PlugRequireHeader do
   import Plug.Conn
   alias Plug.Conn.Status
 
-  @vsn "0.3.0"
+  @vsn "0.3.1"
   @doc false
   def version, do: @vsn
 

mix.exs

@@ -4,7 +4,7 @@ defmodule PlugRequireHeader.Mixfile do
   def project do
     [
       app: :plug_require_header,
-      version: "0.3.0",
+      version: "0.3.1",
       name: "PlugRequireHeader",
       source_url: "https://github.com/DevL/plug_require_header",
       elixir: "~> 1.0",