diff --git a/backend/.env.example b/backend/.env.example
index 6a51ae1..1609ebd 100644
--- a/backend/.env.example
+++ b/backend/.env.example
@@ -3,9 +3,10 @@ PORT=8090
 CORS_ALLOWED_ORIGINS=http://localhost:5173
 
 # Postgres, Zitadel and SeaweedFS come from the shared ../../Infrastructure
-# stack (`make dev-infra`), not from a container in this repo. Credentials
-# must match Infrastructure's own .env.
-DATABASE_URL=postgres://postgres:postgres@host.docker.internal:5432/dockermanager_db?sslmode=disable
+# stack (`make dev-infra`), not from a container in this repo. docker-manager
+# has its own role there, owner of dockermanager_db only; its password must
+# match Infrastructure's DOCKERMANAGER_DB_PASSWORD.
+DATABASE_URL=postgres://dockermanager:dockermanager@host.docker.internal:5432/dockermanager_db?sslmode=disable
 
 # Not wired into the backend yet (see README). These point at Infrastructure's
 # Zitadel for when OIDC login is implemented.