diff --git a/leaflet-osm.js b/leaflet-osm.js
index 9d7d939..1801ac6 100644
--- a/leaflet-osm.js
+++ b/leaflet-osm.js
@@ -71,7 +71,7 @@ L.OSM.HOT = L.OSM.TileLayer.extend({
 
 L.OSM.TracestrackTopo = L.OSM.TileLayer.extend({
   options: {
-    url: 'https://tile.tracestrack.com/topo__/{z}/{x}/{y}.png?key={apikey}',
+    url: 'https://tile.tracestrack.com/topo__/{z}/{x}/{y}.webp?key={apikey}',
     maxZoom: 19,
     attribution: '© <a href="https://www.openstreetmap.org/copyright" target="_blank">OpenStreetMap</a> contributors. Tiles courtesy of <a href="https://www.tracestrack.com/" target="_blank">Tracestrack Maps</a>'
   }
diff --git a/test/osm_test.js b/test/osm_test.js
index 36597fa..aab64b5 100644
--- a/test/osm_test.js
+++ b/test/osm_test.js
@@ -62,7 +62,7 @@ describe("L.OSM.OPNVKarte", function () {
 
 describe("L.OSM.TracestrackTopo", function () {
   it("has the appropriate URL", function () {
-    new L.OSM.TracestrackTopo()._url.should.eq('https://tile.tracestrack.com/topo__/{z}/{x}/{y}.png?key={apikey}');
+    new L.OSM.TracestrackTopo()._url.should.eq('https://tile.tracestrack.com/topo__/{z}/{x}/{y}.webp?key={apikey}');
   });
 
   it("has the appropriate attribution", function () {