diff --git a/examples/mapbox-layer.js b/examples/mapbox-layer.js
index 0f1035a16c..e2f93463d5 100644
--- a/examples/mapbox-layer.js
+++ b/examples/mapbox-layer.js
@@ -1,6 +1,7 @@
 import GeoJSON from '../src/ol/format/GeoJSON.js';
 import Layer from '../src/ol/layer/Layer.js';
 import Map from '../src/ol/Map.js';
+import Source from '../src/ol/source/Source.js';
 import VectorLayer from '../src/ol/layer/Vector.js';
 import VectorSource from '../src/ol/source/Vector.js';
 import View from '../src/ol/View.js';