diff --git a/admin-users/tasks/main.yml b/admin-users/tasks/main.yml
index 389fe9d5..e9f5dcdc 100644
--- a/admin-users/tasks/main.yml
+++ b/admin-users/tasks/main.yml
@@ -1,5 +1,9 @@
 ---
 
+- fail:
+    msg: "Error: empty variable 'admin_users'!"
+  when: admin_users == {}
+
 - include: adduser_debian.yml user={{ item.value }}
   with_dict: "{{ admin_users }}"
   when: ansible_distribution == "Debian"