Index: /applications/editors/josm/plugins/routes/src/org/openstreetmap/josm/plugins/routes/RoutesPlugin.java
===================================================================
--- /applications/editors/josm/plugins/routes/src/org/openstreetmap/josm/plugins/routes/RoutesPlugin.java	(revision 33605)
+++ /applications/editors/josm/plugins/routes/src/org/openstreetmap/josm/plugins/routes/RoutesPlugin.java	(revision 33606)
@@ -16,4 +16,5 @@
 import org.openstreetmap.josm.gui.MainApplication;
 import org.openstreetmap.josm.gui.layer.Layer;
+import org.openstreetmap.josm.gui.layer.LayerManager;
 import org.openstreetmap.josm.gui.layer.LayerManager.LayerAddEvent;
 import org.openstreetmap.josm.gui.layer.LayerManager.LayerChangeListener;
@@ -80,8 +81,11 @@
 		Layer layer = e.getAddedLayer();
 		if (layer instanceof OsmDataLayer) {
+			LayerManager lm = e.getSource();
 			for (RouteLayer routeLayer : routeLayers) {
-				if (!e.getSource().containsLayer(routeLayer)) {
+				if (!lm.containsLayer(routeLayer)) {
 					SwingUtilities.invokeLater(() -> {
-						e.getSource().addLayer(routeLayer);
+						if (!lm.containsLayer(routeLayer)) {
+							lm.addLayer(routeLayer);
+						}
 					});
 				}