diff --git a/docker-compose.coolify.yml b/docker-compose.coolify.yml
index 9daf60a..75ceb8f 100644
--- a/docker-compose.coolify.yml
+++ b/docker-compose.coolify.yml
@@ -32,6 +32,8 @@ services:
       REDIS_URL: ${REDIS_URL}
       AUTH_SECRET: ${AUTH_SECRET}
       AUTH_URL: ${AUTH_URL}
+      # Hinter dem Coolify/Traefik-Proxy zwingend für Auth.js v5 (sonst UntrustedHost).
+      AUTH_TRUST_HOST: ${AUTH_TRUST_HOST:-true}
       S3_ENDPOINT: ${S3_ENDPOINT}
       S3_ACCESS_KEY: ${S3_ACCESS_KEY}
       S3_SECRET_KEY: ${S3_SECRET_KEY}