diff --git a/docker/rootfs/etc/letsencrypt.ini b/docker/rootfs/etc/letsencrypt.ini
index aae53b90..0bd74967 100644
--- a/docker/rootfs/etc/letsencrypt.ini
+++ b/docker/rootfs/etc/letsencrypt.ini
@@ -4,3 +4,4 @@ webroot-path = /data/letsencrypt-acme-challenge
 key-type = ecdsa
 elliptic-curve = secp384r1
 preferred-chain = ISRG Root X1
+rsa-key-size = 4096