diff --git a/README.md b/README.md
index 6734c6e..c7bce0f 100644
--- a/README.md
+++ b/README.md
@@ -237,10 +237,11 @@ HOST_DATA_DIR=/srv/upaas/data
 ```
 
 Other settings from [Configuration](#configuration) go in the same file, except
-`PORT` and `UPAAS_DATA_DIR`: the compose file sets them to 8080 and
-`/var/lib/upaas`, overriding `.env`, to match its port mapping, healthcheck and
-data directory mount. Then run `docker compose up -d` from the repo root;
-`docker compose ps` shows the container as healthy once `/health` answers.
+`PORT`, `UPAAS_PORT` and `UPAAS_DATA_DIR`: the compose file sets both port
+settings to 8080 and `UPAAS_DATA_DIR` to `/var/lib/upaas`, overriding `.env`, to
+match its port mapping, healthcheck and data directory mount. Then run
+`docker compose up -d` from the repo root; `docker compose ps` shows the
+container as healthy once `/health` answers.
 
 **Important**: `HOST_DATA_DIR` **must** be an **absolute path** on the host. It
 is bind-mounted into the container and passed as `UPAAS_HOST_DATA_DIR` so that
diff --git a/TODO.md b/TODO.md
index da459cb..ff43640 100644
--- a/TODO.md
+++ b/TODO.md
@@ -20,6 +20,11 @@ regress.
 
 # Completed Steps
 
+- 2026-09-29: `docker-compose.yml` now sets `UPAAS_PORT` to 8080 as well as
+  `PORT`, since upaas reads `UPAAS_PORT` first and a `UPAAS_PORT` in `.env` made
+  it listen away from the port mapping and healthcheck; the README's Compose
+  section names both (#230).
+
 - 2026-09-29: The README Configuration table now lists every setting upaas
   reads, adding `UPAAS_MAINTENANCE_MODE`, `UPAAS_SESSION_SECRET` and
   `UPAAS_CORS_ORIGINS`, and gives the real default and effect of each:
diff --git a/docker-compose.yml b/docker-compose.yml
index 51a31cf..f33a2b6 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -7,9 +7,11 @@ services:
     # Every line of .env is passed to upaas as an environment variable.
     env_file: .env
     environment:
-      # Overrides any PORT in .env, so upaas listens where the port mapping
-      # and healthcheck below expect it.
+      # Override any PORT or UPAAS_PORT in .env, so upaas listens where the
+      # port mapping and healthcheck below expect it. Both are set because
+      # upaas reads UPAAS_PORT first.
       PORT: "8080"
+      UPAAS_PORT: "8080"
       # Overrides any UPAAS_DATA_DIR in .env, so the database stays on the
       # HOST_DATA_DIR mount below instead of inside the container.
       UPAAS_DATA_DIR: /var/lib/upaas