diff --git a/README.md b/README.md
index f2a89a9..821a204 100644
--- a/README.md
+++ b/README.md
@@ -10,6 +10,7 @@ Deployed on [Coolify](https://coolify.io) via Docker Compose.
    - `DB_PASSWORD` — strong random password
    - `INITIAL_API_KEY` — initial API key (`openssl rand -hex 32`)
    - `TIMEZONE` — your timezone
+   - `DEFAULT_INVALID_SHORT_URL_REDIRECT` — (optional) URL to redirect to when a short URL is not found
 3. In the resource's **Domains** settings, enter your domain with the container port appended: `https://s.example.com:8080`
 4. Deploy.