diff --git a/deployments/examples/ocis_wopi/docker-compose.yml b/deployments/examples/ocis_wopi/docker-compose.yml
index c01e6d2c2..d3f3c285a 100644
--- a/deployments/examples/ocis_wopi/docker-compose.yml
+++ b/deployments/examples/ocis_wopi/docker-compose.yml
@@ -81,7 +81,7 @@ services:
       NOTIFICATIONS_SMTP_PORT: 2500
       NOTIFICATIONS_SMTP_SENDER: oCIS notifications <notifications@${OCIS_DOMAIN:-ocis.owncloud.test}>
       NOTIFICATIONS_SMTP_USERNAME: notifications@${OCIS_DOMAIN:-ocis.owncloud.test}
-      NOTIFICATIONS_SMTP_INSECURE: true # the mail catcher uses self signed certificates
+      NOTIFICATIONS_SMTP_INSECURE: "true" # the mail catcher uses self signed certificates
     volumes:
       - ./config/ocis/app-registry.yaml:/etc/ocis/app-registry.yaml
       - ocis-config:/etc/ocis