diff --git a/tasks/setup.yml b/tasks/setup.yml
index d17a889..586ee7f 100644
--- a/tasks/setup.yml
+++ b/tasks/setup.yml
@@ -43,7 +43,7 @@
         dest: "{{ alertmanager_config_dir }}/alertmanager.yml"
         owner: "{{ alertmanager_user }}"
         group: "{{ alertmanager_user }}"
-        mode: 0640
+        mode: 0600
         validate: "{{ alertmanager_base_dir }}/amtool check-config %s"
       notify: __alertmanager_restart