diff --git a/lib/map.js b/lib/map.js
index 5be38ec..b5cbce7 100644
--- a/lib/map.js
+++ b/lib/map.js
@@ -275,7 +275,7 @@ define(["map/clientlayer", "map/labelslayer",
       map = L.map(el, options);
       var now = new Date();
       config.mapLayers.forEach(function (item, i) {
-        if (item.config.start <= now.getHours() || item.config.end > now.getHours()) {
+        if ((typeof item.config.start === 'number' && item.config.start <= now.getHours()) || (typeof item.config.end === 'number' && item.config.end > now.getHours())) {
           item.config.order = item.config.start * -1;
         } else {
           item.config.order = i;