diff --git a/postgres-backup-s3/README.md b/postgres-backup-s3/README.md
index a5339de..e963929 100644
--- a/postgres-backup-s3/README.md
+++ b/postgres-backup-s3/README.md
@@ -28,6 +28,7 @@ pgbackups3:
     S3_SECRET_ACCESS_KEY: secret
     S3_BUCKET: my-bucket
     S3_PREFIX: backup
+    POSTGRES_HOST: host
     POSTGRES_DATABASE: dbname
     POSTGRES_USER: user
     POSTGRES_PASSWORD: password