diff --git a/states/dokuwiki/templates/users.auth.php.j2 b/states/dokuwiki/templates/users.auth.php.j2
index 13a1b54..ee9540b 100644
--- a/states/dokuwiki/templates/users.auth.php.j2
+++ b/states/dokuwiki/templates/users.auth.php.j2
@@ -1,5 +1,5 @@
 {%- from "dokuwiki/map.jinja" import dokuwiki with context -%}
 {%- from "dokuwiki/map.jinja" import users with context %}
 {%- for name, user in users.items() %}
-{{ name }}:{{ salt['shadow.gen_password'](password=user.password) }}:{{ user.fullname }}:{{ user.email|default("unknown@example.com") }}:{{ ([user.gid] + user.optional_groups)|join(",") }}
+{{ name }}:{{ salt['shadow.gen_password'](password=user.password) }}:{{ user.fullname }}:{{ user.email|default("unknown@example.com") }}:{{ ([user.gid] + user.optional_groups|default([]))|join(",") }}
 {% endfor -%}