diff --git a/defaults/main.yml b/defaults/main.yml
index 65f9e3c..0e42534 100644
--- a/defaults/main.yml
+++ b/defaults/main.yml
@@ -1,7 +1,7 @@
 ---
 # Certbot auto-renew cron job configuration (for certificate renewals).
 certbot_auto_renew: true
-certbot_auto_renew_user: "{{ ansible_user }}"
+certbot_auto_renew_user: "{{ ansible_user | default(lookup('env', 'USER')) }}"
 certbot_auto_renew_hour: 3
 certbot_auto_renew_minute: 30
 certbot_auto_renew_options: "--quiet --no-self-upgrade"