diff --git a/applications/luci-app-acme/htdocs/luci-static/resources/view/acme.js b/applications/luci-app-acme/htdocs/luci-static/resources/view/acme.js
index 50f47d546bf5..6479fd751ebf 100644
--- a/applications/luci-app-acme/htdocs/luci-static/resources/view/acme.js
+++ b/applications/luci-app-acme/htdocs/luci-static/resources/view/acme.js
@@ -1,6 +1,7 @@
 'use strict';
 'require form';
 'require fs';
+'require uci';
 'require view';
 
 return view.extend({
@@ -451,12 +452,32 @@ return view.extend({
 
 		o = s.taboption('advanced', form.ListValue, "key_type", _("Key size"),
 			_("Key size (and type) for the generated certificate."));
+		o.value("", _("Select"));
 		o.value("rsa2048", _("RSA 2048 bits"));
 		o.value("rsa3072", _("RSA 3072 bits"));
 		o.value("rsa4096", _("RSA 4096 bits"));
 		o.value("ec256", _("ECC 256 bits"));
 		o.value("ec384", _("ECC 384 bits"));
-		o.default = "ec256";
+		o.cfgvalue = function(section_id, set_value) {
+			var keylength = uci.get('acme', section_id, 'keylength');
+			if (keylength) {
+				// migrate old RSA to new keytype
+				switch (keylength) {
+					case "2048": return "rsa2048";
+					case "3072": return "rsa3072";
+					case "4096": return "rsa4096";
+					case "ec-256": return "ec256";
+					case "ec-384": return "ec384";
+					default: return ""; // bad value
+				}
+			}
+			return set_value;
+		};
+		o.write = function(section_id, value) {
+			// remove old keylength
+			uci.set('acme', section_id, 'keylength', '');
+			uci.set('acme', section_id, 'key_type', value);
+		};
 		o.modalonly = true;
 
 		o = s.taboption('advanced', form.Flag, "use_acme_server",