diff --git a/docker-compose.yml b/docker-compose.yml
index 4e729ab..2420d81 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -16,12 +16,17 @@ services:
       POSTGRES_PASSWORD: ${POSTGRES_PASSWORD:?set POSTGRES_PASSWORD in the stack}
       POSTGRES_DB: vmselector
     volumes:
-      - db_data:/var/lib/postgresql/data
+      # Postgres 18 moved PGDATA to /var/lib/postgresql/18/docker and its declared
+      # VOLUME to /var/lib/postgresql. Mounting the pre-18 /var/lib/postgresql/data
+      # leaves the real data outside the volume, and trips the entrypoint.
+      - db_data:/var/lib/postgresql
     healthcheck:
       test: ['CMD-SHELL', 'pg_isready -U postgres -d vmselector']
       interval: 5s
       timeout: 5s
       retries: 10
+      # initdb runs on the very first boot: do not count failures before it is done
+      start_period: 30s
     networks: [internal]
 
   # Runs once per deployment, before the app: applies any new migration, then exits