diff --git a/src/util/scroll-view.ts b/src/util/scroll-view.ts
index 3f717ab2aef..3fff5c72101 100644
--- a/src/util/scroll-view.ts
+++ b/src/util/scroll-view.ts
@@ -35,7 +35,7 @@ export class ScrollView {
       velocityX: 0,
       directionY: 'down',
       directionX: null,
-      domWrite: function(fn: DomCallback, ctx?: any) {
+      domWrite: function(fn: DomCallback, ctx?: any): void {
         _dom.write(fn, ctx);
       },
       contentElement: null,