diff --git a/web/annotation_layer_builder.js b/web/annotation_layer_builder.js
index 9a77bf5af..ceca000b9 100644
--- a/web/annotation_layer_builder.js
+++ b/web/annotation_layer_builder.js
@@ -137,4 +137,5 @@ DefaultAnnotationLayerFactory.prototype = {
 };
 
 exports.AnnotationLayerBuilder = AnnotationLayerBuilder;
+exports.DefaultAnnotationLayerFactory = DefaultAnnotationLayerFactory;
 }));