diff --git a/README.md b/README.md
index 97a0926..9b51a28 100644
--- a/README.md
+++ b/README.md
@@ -73,6 +73,13 @@ Depending on the configured url you can initiate the request through:
 
     /auth/twitter
 
+## Development mode
+
+As noted when registering your application on the Twitter Developer site, you need to explicitly specify the `oauth_callback` url.  While in development, this is an example url you need to enter.
+
+    Website - http://127.0.0.1
+    Callback URL - http://127.0.0.1:4000/auth/twitter/callback
+
 ## License
 
 Please see [LICENSE](https://github.com/ueberauth/ueberauth_twitter/blob/master/LICENSE) for licensing details.