diff --git a/types/mapbox-gl/index.d.ts b/types/mapbox-gl/index.d.ts
index 4cfdf986bf..5f64b7470b 100644
--- a/types/mapbox-gl/index.d.ts
+++ b/types/mapbox-gl/index.d.ts
@@ -464,6 +464,8 @@ declare namespace mapboxgl {
         anchor?: Anchor;
 
         offset?: number | PointLike | { [key: string]: PointLike; };
+
+        className?: string;
     }
 
     export interface Style {
diff --git a/types/mapbox-gl/mapbox-gl-tests.ts b/types/mapbox-gl/mapbox-gl-tests.ts
index fa62007088..87297effda 100644
--- a/types/mapbox-gl/mapbox-gl-tests.ts
+++ b/types/mapbox-gl/mapbox-gl-tests.ts
@@ -225,7 +225,7 @@ map.addLayer({
 /**
  * Popup
  */
-var popup = new mapboxgl.Popup({closeOnClick: false, closeButton: true, anchor: 'top-right', offset: {'top': [0,0], 'bottom': [25,-50]} })
+var popup = new mapboxgl.Popup({closeOnClick: false, closeButton: true, anchor: 'top-right', offset: {'top': [0,0], 'bottom': [25,-50]}, className: 'custom-class' })
 	.setLngLat([-50, 50])
 	.setHTML('<h1>Hello World!</h1>')
 	.addTo(map);