diff --git a/lib/basic_signup_whitelist.ex b/lib/basic_signup_whitelist.ex
index 45c05e5..4a02d1f 100644
--- a/lib/basic_signup_whitelist.ex
+++ b/lib/basic_signup_whitelist.ex
@@ -18,6 +18,7 @@ defmodule BasicSignupWhitelist do
 
   ## Examples
 
+      iex> System.delete_env("SIGNUP_ALLOWED_EMAILS")
       iex> BasicSignupWhitelist.mail_whitelisted("joe@example.com")
       false