diff --git a/src/renderer/loaders/groundnet_loader.js b/src/renderer/loaders/groundnet_loader.js
index 927dcee..1c3bb26 100644
--- a/src/renderer/loaders/groundnet_loader.js
+++ b/src/renderer/loaders/groundnet_loader.js
@@ -106,7 +106,7 @@ exports.readGroundnetXML = function (fDir, icao, force) {
                 p => ({index: Number(p.attrs.index), name: String(p.attrs.name), number: String(p.attrs.number), type: String(p.attrs.type)}
             )).sort((p1, p2) => {
                 if (p1.name === p2.name) {
-                    return p1.number - p2.number
+                    return p1.number?p1.number.localeCompare(p2.number):-1;
                 } else {
                   return p1.name.localeCompare(p2.name)
                 }}));