Index: trunk/src/org/openstreetmap/josm/gui/layer/markerlayer/ImageMarker.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/layer/markerlayer/ImageMarker.java	(revision 18592)
+++ trunk/src/org/openstreetmap/josm/gui/layer/markerlayer/ImageMarker.java	(revision 18593)
@@ -107,5 +107,5 @@
 
     private Supplier<RemoteEntry> getLastImage() {
-        int index = this.parentLayer.data.indexOf(this);
+        int index = Math.max(0, this.parentLayer.data.indexOf(this));
         for (int i = this.parentLayer.data.size() - 1; i >= index; i--) {
             Marker marker = this.parentLayer.data.get(i);