diff --git a/README.md b/README.md
index f8c6e33..164255e 100644
--- a/README.md
+++ b/README.md
@@ -7,6 +7,7 @@ Docker-compose file to be used with Grist.
 GRIST_SESSION_SECRET=
 GRIST_DEFAULT_EMAIL=
 APP_HOME_URL=
+PORT=
 ```
 
 ## OIDC