diff --git a/docs/CONFIG.md b/docs/CONFIG.md
index 91e625b..c46dbd5 100644
--- a/docs/CONFIG.md
+++ b/docs/CONFIG.md
@@ -17,6 +17,7 @@ You can configure MailHog using command line options or environment variables:
 | MH_STORAGE          | -storage        | memory          | Set message storage: memory / mongodb / maildir
 | MH_OUTGOING_SMTP    | -outgoing-smtp  |                 | JSON file defining outgoing SMTP servers
 | MH_UI_WEB_PATH      | -ui-web-path    |                 | WebPath under which the ui is served (without leading or trailing slahes), e.g. 'mailhog'
+| MH_AUTH_FILE        | -auth-file      |                 | A username:bcryptpw mapping file
 
 #### Note on HTTP bind addresses