diff --git a/deploy/docker/docker-compose.yml b/deploy/docker/docker-compose.yml
index 17eef14de0..0d5e575432 100644
--- a/deploy/docker/docker-compose.yml
+++ b/deploy/docker/docker-compose.yml
@@ -19,7 +19,9 @@ services:
       POSTGRES_USER: fsh
       POSTGRES_PASSWORD: ${POSTGRES_PASSWORD:?POSTGRES_PASSWORD is required}
     volumes:
-      - pg_data:/var/lib/postgresql/data
+      # The 18+ images keep PGDATA in a versioned subdirectory (/var/lib/postgresql/18/docker) and
+      # refuse to start with a mount at the old /var/lib/postgresql/data, even on an empty volume.
+      - pg_data:/var/lib/postgresql
       - ./postgres-init:/docker-entrypoint-initdb.d:ro
     healthcheck:
       test: ["CMD-SHELL", "pg_isready -U fsh -d fsh"]
diff --git a/deploy/docker/postgres-init/01-create-databases.sql b/deploy/docker/postgres-init/01-create-databases.sql
index 429622701e..5aadc12a50 100644
--- a/deploy/docker/postgres-init/01-create-databases.sql
+++ b/deploy/docker/postgres-init/01-create-databases.sql
@@ -1,5 +1,5 @@
 -- Postgres init for fullstackhero
--- This file runs only on first boot (when /var/lib/postgresql/data is empty).
+-- This file runs only on first boot (when the data directory under /var/lib/postgresql is empty).
 -- The `fsh` database itself is created by POSTGRES_DB= in the compose env;
 -- we just add the extensions the framework relies on.