diff --git a/README.md b/README.md
index b78d62a..50ad885 100644
--- a/README.md
+++ b/README.md
@@ -20,6 +20,24 @@ After you are done, run this in your shell to fetch the new dependency:
 $ mix deps.get
 ```
 
+## Configuration
+
+You can configure facebook.ex in your mix `config.exs` (or, if you're using the Phoenix Framework, in your `dev/test/prod.exs`, respectively) with the following keys, which state the library defaults:
+```
+config :facebook,
+  appsecret: nil,
+  graph_url: "https://graph.facebook.com",
+  graph_video_url: "https://graph-video.facebook.com"
+```
+For graph_url and video_graph_url, Facebook automatically uses the oldest active Graph API version available if you don't specify a version in the url. You may use versioned urls to pin your calls to a specific API versions (recommended), e.g. like so:
+```
+  graph_url: "https://graph.facebook.com/v2.11",
+  graph_video_url: "https://graph-video.facebook.com/v2.8"
+```
+Note that you *must not* end the urls with a slash or the requests will fail (Facebook will report an error about unknown url components)!
+
+Supplying an appsecret is optional. If you supply it, an [appsecret_proof](https://developers.facebook.com/docs/graph-api/securing-requests) will be submitted along with the Graph API requests. The appsecret can be changed (or set) at runtime using `Facebook.set_appsecret("<app secret>")`.
+
 ## Usage
 
 1. Register an application on [developer.facebook.com](https://developer.facebook.com)
diff --git a/mix.exs b/mix.exs
index a8bc5b3..1410cd8 100644
--- a/mix.exs
+++ b/mix.exs
@@ -23,8 +23,8 @@ defmodule Facebook.Mixfile do
       applications: [:httpoison, :json, :logger],
       env: [
         env: :dev,
-        graph_url: "https://graph.facebook.com/v2.9",
-        graph_video_url: "https://graph-video.facebook.com/v2.9",
+        graph_url: "https://graph.facebook.com",
+        graph_video_url: "https://graph-video.facebook.com",
         appsecret: nil
       ]
     ]