diff --git a/umap/static/umap/js/umap.js b/umap/static/umap/js/umap.js
index d260fc70..b3ca3b5c 100644
--- a/umap/static/umap/js/umap.js
+++ b/umap/static/umap/js/umap.js
@@ -790,7 +790,7 @@ U.Map = L.Map.extend({
     return L.Map.prototype.setMaxBounds.call(this, bounds)
   },
 
-  createDataLayer: function (options, sync) {
+  createDataLayer: function (options = {}, sync = true) {
     options.name = options.name || `${L._('Layer')} ${this.datalayers_index.length + 1}`
     const datalayer = new U.DataLayer(this, options, sync)