diff --git a/cmd/mtwebmapper/web/index.html b/cmd/mtwebmapper/web/index.html
index 43cad34..daafae3 100644
--- a/cmd/mtwebmapper/web/index.html
+++ b/cmd/mtwebmapper/web/index.html
@@ -136,7 +136,7 @@ manualUpdateControl = L.easyButton('fa-refresh',
         for (var i = 0; i < tiles.length; i++) {
             var img = tiles[i];
             var cl = img.getAttribute("class");
-            if (cl.contains("leaflet-tile-loaded")) {
+            if (cl.indexOf("leaflet-tile-loaded") >= 0) {
                 var src = img.src;
                 var idx = src.lastIndexOf("#");
                 if (idx >= 0) {
diff --git a/cmd/mtwebmapper/web/js/auto-update.js b/cmd/mtwebmapper/web/js/auto-update.js
index 9f28925..fee0617 100644
--- a/cmd/mtwebmapper/web/js/auto-update.js
+++ b/cmd/mtwebmapper/web/js/auto-update.js
@@ -137,7 +137,7 @@ L.Control.AutoUpdate = L.Control.extend({
             for (var i = 0; i < tiles.length; i++) {
                 var img = tiles[i];
                 var cl = img.getAttribute('class');
-                if (!cl.contains('leaflet-tile-loaded')) {
+                if (cl.indexOf('leaflet-tile-loaded') < 0) {
                     continue;
                 }
                 var src = img.src;