diff --git a/umap/static/umap/js/umap.js b/umap/static/umap/js/umap.js
index 162d2763..cd4845c6 100644
--- a/umap/static/umap/js/umap.js
+++ b/umap/static/umap/js/umap.js
@@ -33,6 +33,7 @@ U.Map = L.Map.extend({
   includes: [ControlsMixin],
 
   initialize: function (el, geojson) {
+    this.sync = new U.SyncEngine(this)
     // Locale name (pt_PT, en_US…)
     // To be used for Django localization
     if (geojson.properties.locale) L.setLocale(geojson.properties.locale)
@@ -155,7 +156,6 @@ U.Map = L.Map.extend({
       this.options.onLoadPanel = 'datafilters'
     }
 
-    this.sync = new U.SyncEngine(this)
     let isDirty = false // self status
     try {
       Object.defineProperty(this, 'isDirty', {
diff --git a/umap/static/umap/js/umap.layer.js b/umap/static/umap/js/umap.layer.js
index 544a6382..19cbba79 100644
--- a/umap/static/umap/js/umap.layer.js
+++ b/umap/static/umap/js/umap.layer.js
@@ -1375,6 +1375,12 @@ U.DataLayer = L.Evented.extend({
     )
     popupFieldset.appendChild(builder.build())
 
+    // XXX I'm not sure **why** this is needed (as it's set during `this.initialize`)
+    // but apparently it's needed.
+    if (!U.Utils.isObject(this.options.remoteData)) {
+      this.options.remoteData = {}
+    }
+
     const remoteDataFields = [
       [
         'options.remoteData.url',
diff --git a/umap/tests/integration/test_collaborative_editing.py b/umap/tests/integration/test_collaborative_editing.py
index d441c68e..3f5b0c31 100644
--- a/umap/tests/integration/test_collaborative_editing.py
+++ b/umap/tests/integration/test_collaborative_editing.py
@@ -5,7 +5,7 @@ from time import sleep
 
 from playwright.sync_api import expect
 
-from umap.models import DataLayer, Map
+from umap.models import DataLayer
 
 from ..base import DataLayerFactory, MapFactory