diff --git a/.env.example b/.env.example
index bd2b4753f..59127f810 100644
--- a/.env.example
+++ b/.env.example
@@ -17,4 +17,9 @@ GITHUB_APP_WEBHOOK_SECRET=
 GITHUB_APP_PRIVATE_KEY=
 
 FABRO_SLACK_APP_TOKEN=
-FABRO_SLACK_BOT_TOKEN=
\ No newline at end of file
+FABRO_SLACK_BOT_TOKEN=
+
+# Public hostname for the prod docker-compose stack. Leave unset for
+# localhost (Caddy will serve plain HTTP); set to a real DNS name to
+# let Caddy auto-provision a Let's Encrypt certificate.
+FABRO_DOMAIN=
\ No newline at end of file