diff --git a/tasks/main.yml b/tasks/main.yml
index c9987de..206ad6f 100644
--- a/tasks/main.yml
+++ b/tasks/main.yml
@@ -3,7 +3,7 @@
   user:
     name: "{{ item.name }}"
     shell: "{{ item.shell | default('/usr/sbin/nologin') }}"
-    groups: "{{ item.secondary_groups | default('') }}"
+    groups: "{{ (item.secondary_groups | join(',')) | default('') }}"
     comment: "{{ item.comment | default('') }}"
     home: "{{ item.home }}"
     generate_ssh_key: yes
@@ -34,7 +34,7 @@
   user:
     name: "{{ item.name }}"
     shell: "{{ item.shell | default('/usr/sbin/nologin') }}"
-    groups: "{{ item.secondary_groups | default('') }}"
+    groups: "{{ (item.secondary_groups | join(',')) | default('') }}"
     comment: "{{ item.comment | default('') }}"
     uid: "{{ item.uid | default(omit) }}"
     home: "{{ item.home }}"