diff --git a/.env.sample b/.env.sample
index ffd2c20..67085ae 100644
--- a/.env.sample
+++ b/.env.sample
@@ -1,6 +1,10 @@
 TYPE=custom-html-tiny
 
 DOMAIN={{ .Domain }}
+
+## Domain aliases
+#EXTRA_DOMAINS=', `www.custom-html.example.com`'
+
 LETS_ENCRYPT_ENV=production
 HTTP_SUBDIR=
 COMPOSE_FILE="compose.yml"