diff --git a/lib/google-jwt-certs.js b/lib/google-jwt-certs.js
index <HASH>..<HASH> 100644
--- a/lib/google-jwt-certs.js
+++ b/lib/google-jwt-certs.js
@@ -45,8 +45,10 @@ function reloadCertificates() {
 reloadCertificates();
 
 // every five minutes check if it's already been a day since last reload
-// because when developing, if the computer sleeps, interval timers may pause
-setInterval(reloadCertificates, 5 * 60 * 1000);
+// because when developing, if the computer sleeps, interval timers may pause.
+// unref() makes sure this setInterval doesn't prevent node from
+// exiting when everything else is done
+setInterval(reloadCertificates, 5 * 60 * 1000).unref();
 
 module.exports = {
   /* for a given key ID (kid),
don't prevent node from stopping