Index: /applications/editors/josm/plugins/mapillary/src/org/openstreetmap/josm/plugins/mapillary/MapillaryData.java
===================================================================
--- /applications/editors/josm/plugins/mapillary/src/org/openstreetmap/josm/plugins/mapillary/MapillaryData.java	(revision 31882)
+++ /applications/editors/josm/plugins/mapillary/src/org/openstreetmap/josm/plugins/mapillary/MapillaryData.java	(revision 31883)
@@ -47,6 +47,6 @@
    */
   protected MapillaryData() {
-    this.images = new ConcurrentSkipListSet<>();
-    this.multiSelectedImages = new ConcurrentSkipListSet<>();
+    this.images = Collections.newSetFromMap(new ConcurrentHashMap<MapillaryAbstractImage, Boolean>());
+    this.multiSelectedImages = Collections.newSetFromMap(new ConcurrentHashMap<MapillaryAbstractImage, Boolean>());
     this.selectedImage = null;
 
@@ -383,5 +383,6 @@
    */
   public synchronized void setImages(Set<MapillaryAbstractImage> images) {
-    this.images = new ConcurrentSkipListSet<>(images);
+    this.images.clear();
+    this.images.addAll(images);
   }