diff --git a/admin-guide/configuration/icinga2.md b/admin-guide/configuration/icinga2.md
index dd29c752..9a9a0445 100644
--- a/admin-guide/configuration/icinga2.md
+++ b/admin-guide/configuration/icinga2.md
@@ -16,4 +16,5 @@ icinga2::enable: true
 (which will be default at some point, e.g. for RHEL9).
 
 Users and groups in `aaa::admins` and `icinga2::web::users` will have access to these nodes on [monitoring.psi.ch](https://monitoring.psi.ch).
+Prefix the group name with a `%` to distinguish them from users.