diff --git a/examples/resources/mapbox-streets-v6-style.js b/examples/resources/mapbox-streets-v6-style.js
index c7f6c4ad2f..af123f84b9 100644
--- a/examples/resources/mapbox-streets-v6-style.js
+++ b/examples/resources/mapbox-streets-v6-style.js
@@ -1,3 +1,6 @@
+// Styles for the mapbox-streets-v6 vector tile data set. Loosely based on
+// http://a.tiles.mapbox.com/v4/mapbox.mapbox-streets-v6.json
+
 function createMapboxStreetsV6Style() {
   var fill = new ol.style.Fill({color: ''});
   var stroke = new ol.style.Stroke({color: '', width: 1});