diff --git a/README.md b/README.md
index 565d056..f7a2014 100644
--- a/README.md
+++ b/README.md
@@ -181,7 +181,7 @@ Short version:
 cp .env.example .env   # set DB_PASSWORD
 sudo docker compose up -d postgres setup migrate
 DB_HOST=localhost DB_PORT=5432 DB_NAME=timetracker \
-    DB_USERNAME=timetracker DB_PASSWORD=$(grep ^DB_PASSWORD= .env | cut -d= -f2-) \
+    DB_USER=timetracker DB_PASSWORD=$(grep ^DB_PASSWORD= .env | cut -d= -f2-) \
     npx vitest run tests/integration
 sudo docker compose down -v   # cleanup
 ```
diff --git a/docker-compose.yml b/docker-compose.yml
index 5954304..4e5944a 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -18,13 +18,13 @@ services:
     image: postgres:16-alpine
     restart: unless-stopped
     environment:
-      POSTGRES_USER: ${DB_USERNAME:-timetracker}
+      POSTGRES_USER: ${DB_USER:-timetracker}
       POSTGRES_PASSWORD: ${DB_PASSWORD:?DB_PASSWORD must be set in .env}
       POSTGRES_DB: ${DB_NAME:-timetracker}
     volumes:
       - postgres-data:/var/lib/postgresql/data
     healthcheck:
-      test: ["CMD-SHELL", "pg_isready -U ${DB_USERNAME:-timetracker} -d ${DB_NAME:-timetracker}"]
+      test: ["CMD-SHELL", "pg_isready -U ${DB_USER:-timetracker} -d ${DB_NAME:-timetracker}"]
       interval: 5s
       timeout: 3s
       retries: 10
@@ -43,7 +43,7 @@ services:
         condition: service_healthy
     environment:
       PGHOST: postgres
-      PGUSER: ${DB_USERNAME:-timetracker}
+      PGUSER: ${DB_USER:-timetracker}
       PGPASSWORD: ${DB_PASSWORD}
       PGDATABASE: ${DB_NAME:-timetracker}
     volumes:
@@ -73,7 +73,7 @@ services:
       DB_HOST: postgres
       DB_PORT: 5432
       DB_NAME: ${DB_NAME:-timetracker}
-      DB_USERNAME: ${DB_USERNAME:-timetracker}
+      DB_USER: ${DB_USER:-timetracker}
       DB_PASSWORD: ${DB_PASSWORD}
       NODE_ENV: production
     # npx + the locally-installed sequelize-cli — no global install
@@ -96,7 +96,7 @@ services:
       DB_HOST: postgres
       DB_PORT: 5432
       DB_NAME: ${DB_NAME:-timetracker}
-      DB_USERNAME: ${DB_USERNAME:-timetracker}
+      DB_USER: ${DB_USER:-timetracker}
       DB_PASSWORD: ${DB_PASSWORD}
       PORT: 3000
       HOST: 0.0.0.0
diff --git a/tests/integration/README.md b/tests/integration/README.md
index 518b4c3..6daa1bc 100644
--- a/tests/integration/README.md
+++ b/tests/integration/README.md
@@ -23,7 +23,7 @@ sudo docker compose up -d postgres setup migrate
 sudo docker compose ps -a   # postgres: healthy, setup/migrate: Exited (0)
 
 # 3. Run the integration suite with DB vars set.
-export DB_HOST=localhost DB_PORT=5432 DB_NAME=timetracker DB_USERNAME=timetracker
+export DB_HOST=localhost DB_PORT=5432 DB_NAME=timetracker DB_USER=timetracker
 export DB_PASSWORD=$(grep '^DB_PASSWORD=' .env | cut -d= -f2-)
 npx vitest run tests/integration