diff --git a/src/cron.js b/src/cron.js
index ab9a62520..fb695fd34 100644
--- a/src/cron.js
+++ b/src/cron.js
@@ -114,8 +114,9 @@ async function startJobs() {
         start: true
     });
 
+    // randomized over minute an hours, once a day to not hammer Let'sEncrypt on the same schedule
     gJobs.certificateRenew = new CronJob({
-        cronTime: '00 00 */12 * * *', // every 12 hours
+        cronTime: `00 ${parseInt(Math.random()*60)} ${parseInt(Math.random()*24)} * * *`,
         onTick: async () => await safe(cloudron.renewCerts({}, AuditSource.CRON), { debug }),
         start: true
     });