diff --git a/docs/CAPTCHA_SETUP.rst b/docs/CAPTCHA_SETUP.rst
index 19a204d9ce..0c22ee4ff6 100644
--- a/docs/CAPTCHA_SETUP.rst
+++ b/docs/CAPTCHA_SETUP.rst
@@ -7,6 +7,7 @@ Requires a public/private key pair from:
 
 https://developers.google.com/recaptcha/
 
+Must be a reCAPTCHA v2 key using the "I'm not a robot" Checkbox option
 
 Setting ReCaptcha Keys
 ----------------------