diff --git a/docker-compose.yml b/docker-compose.yml
index ec763a2..4e03fd9 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -33,7 +33,7 @@ services:
     image: zammad/zammad-docker-compose:zammad
     labels:
       io.rancher.container.pull_image: always
-      io.rancher.container.start_once: true
+      io.rancher.container.start_once: 'true'
     restart: on-failure
     volumes:
       - data-zammad:/home/zammad