diff --git a/install/lib/installer_base.lib.php b/install/lib/installer_base.lib.php
index 3d49c23871ef998815603259fb55932ef16351e6..20c847b2b67d18b522d6a065ad3a8025de1d6e3c 100644
--- a/install/lib/installer_base.lib.php
+++ b/install/lib/installer_base.lib.php
@@ -3145,11 +3145,11 @@ class installer_base {
 				$out = null;
 				$ret = null;
 				if($conf['nginx']['installed'] == true || $conf['apache']['installed'] == true) {
-					exec("$acme --issue --log $acme_log -w /usr/local/ispconfig/interface/acme -d " . escapeshellarg($hostname) . " $renew_hook", $out, $ret);
+					exec("$acme --issue --keylength 4096 --log $acme_log -w /usr/local/ispconfig/interface/acme -d " . escapeshellarg($hostname) . " $renew_hook", $out, $ret);
 				}
 				// Else, it is not webserver, so we use standalone
 				else {
-					exec("$acme --issue --log $acme_log --standalone -d " . escapeshellarg($hostname) . " $hook", $out, $ret);
+					exec("$acme --issue --keylength 4096 --log $acme_log --standalone -d " . escapeshellarg($hostname) . " $hook", $out, $ret);
 				}
 
 				if($ret == 0 || ($ret == 2 && file_exists($check_acme_file))) {