diff --git a/compose/docker-compose.yml b/compose/docker-compose.yml
index 6b3c1af..8038211 100644
--- a/compose/docker-compose.yml
+++ b/compose/docker-compose.yml
@@ -19,7 +19,7 @@ x-op-app: &app
     RAILS_CACHE_STORE: "memcache"
     OPENPROJECT_CACHE__MEMCACHE__SERVER: "cache:11211"
     OPENPROJECT_RAILS__RELATIVE__URL__ROOT: "${OPENPROJECT_RAILS__RELATIVE__URL__ROOT:-}"
-    DATABASE_URL: "postgres://postgres:p4ssw0rd@db/openproject?pool=20&encoding=unicode&reconnect=true"
+    DATABASE_URL: "${DATABASE_URL:-postgres://postgres:p4ssw0rd@db/openproject?pool=20&encoding=unicode&reconnect=true}"
     RAILS_MIN_THREADS: 4
     RAILS_MAX_THREADS: 16
     USE_PUMA: "true"