diff --git a/docker-compose.yml b/docker-compose.yml
index 9fc67f5..9242fb6 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -55,6 +55,7 @@ services:
       - internal_network
     environment:
       RAILS_ENV: development
+      PRIMARY_DOMAIN: kosmos.org
       REDIS_URL: redis://redis:6379/0
       LDAP_HOST: ldap
       LDAP_PORT: 3389