diff --git a/infrastructure/docker-compose.dev.yml b/infrastructure/docker-compose.dev.yml
index 3401c79..f673f46 100644
--- a/infrastructure/docker-compose.dev.yml
+++ b/infrastructure/docker-compose.dev.yml
@@ -13,7 +13,7 @@ services:
       - ../backend/app:/app/app:ro  # Hot reload for code changes
       - ../data:/app/config
     environment:
-      - DATABASE_URL=postgresql://truehour:truehour@db:5432/truehour
+      - DATABASE_URL=${DATABASE_URL:-postgresql://truehour:truehour@db:5432/truehour}
       - CONFIG_PATH=/app/config/config.json
       - RELOAD=true  # Enable uvicorn auto-reload
     command: ["uvicorn", "app.main:app", "--host", "0.0.0.0", "--port", "8000", "--reload"]
diff --git a/infrastructure/docker-compose.ghcr-develop.yml b/infrastructure/docker-compose.ghcr-develop.yml
index b0a93d2..2997a48 100644
--- a/infrastructure/docker-compose.ghcr-develop.yml
+++ b/infrastructure/docker-compose.ghcr-develop.yml
@@ -21,7 +21,7 @@ services:
     ports:
       - "8000:8000"
     environment:
-      - DATABASE_URL=postgresql://truehour:truehour@db:5432/truehour
+      - DATABASE_URL=${DATABASE_URL:-postgresql://truehour:truehour@db:5432/truehour}
       - DB_PATH=/app/data/aircraft.db
       - ENABLE_FAA_LOOKUP=${ENABLE_FAA_LOOKUP:-false}
     depends_on:
@@ -39,6 +39,9 @@ services:
       - POSTGRES_DB=truehour
       - POSTGRES_USER=truehour
       - POSTGRES_PASSWORD=truehour
+      # postgres:18+ moved PGDATA to /var/lib/postgresql/<major>/docker.
+      # Pin it to the mounted path so the named volume is actually used.
+      - PGDATA=/var/lib/postgresql/data
     volumes:
       - postgres_data:/var/lib/postgresql/data
       - ./init.sql:/docker-entrypoint-initdb.d/init.sql
diff --git a/infrastructure/docker-compose.ghcr.yml b/infrastructure/docker-compose.ghcr.yml
index a89e58c..23f4ee9 100644
--- a/infrastructure/docker-compose.ghcr.yml
+++ b/infrastructure/docker-compose.ghcr.yml
@@ -18,7 +18,7 @@ services:
     ports:
       - "8000:8000"
     environment:
-      - DATABASE_URL=postgresql://truehour:truehour@db:5432/truehour
+      - DATABASE_URL=${DATABASE_URL:-postgresql://truehour:truehour@db:5432/truehour}
       - DB_PATH=/app/data/aircraft.db
       - ENABLE_FAA_LOOKUP=${ENABLE_FAA_LOOKUP:-false}
     depends_on:
@@ -36,6 +36,9 @@ services:
       - POSTGRES_DB=truehour
       - POSTGRES_USER=truehour
       - POSTGRES_PASSWORD=truehour
+      # postgres:18+ moved PGDATA to /var/lib/postgresql/<major>/docker.
+      # Pin it to the mounted path so the named volume is actually used.
+      - PGDATA=/var/lib/postgresql/data
     volumes:
       - postgres_data:/var/lib/postgresql/data
       - ./init.sql:/docker-entrypoint-initdb.d/init.sql
diff --git a/infrastructure/docker-compose.yml b/infrastructure/docker-compose.yml
index 67fe6b8..66eb127 100644
--- a/infrastructure/docker-compose.yml
+++ b/infrastructure/docker-compose.yml
@@ -24,7 +24,7 @@ services:
     volumes:
       - ../data:/app/config  # config.json only
     environment:
-      - DATABASE_URL=postgresql://truehour:truehour@db:5432/truehour
+      - DATABASE_URL=${DATABASE_URL:-postgresql://truehour:truehour@db:5432/truehour}
       - CONFIG_PATH=/app/config/config.json
       - ENABLE_FAA_LOOKUP=${ENABLE_FAA_LOOKUP:-false}
     depends_on:
@@ -46,6 +46,9 @@ services:
       - POSTGRES_USER=${POSTGRES_USER:-truehour}
       - POSTGRES_PASSWORD=${POSTGRES_PASSWORD:-truehour}
       - POSTGRES_DB=${POSTGRES_DB:-truehour}
+      # postgres:18+ moved PGDATA to /var/lib/postgresql/<major>/docker.
+      # Pin it to the mounted path so the named volume is actually used.
+      - PGDATA=/var/lib/postgresql/data
     healthcheck:
       test: ["CMD-SHELL", "pg_isready -U truehour"]
       interval: 5s