Index: trunk/src/org/openstreetmap/josm/gui/layer/OsmDataLayer.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/layer/OsmDataLayer.java	(revision 8806)
+++ trunk/src/org/openstreetmap/josm/gui/layer/OsmDataLayer.java	(revision 8807)
@@ -63,4 +63,5 @@
 import org.openstreetmap.josm.data.osm.Node;
 import org.openstreetmap.josm.data.osm.OsmPrimitive;
+import org.openstreetmap.josm.data.osm.OsmPrimitiveComparator;
 import org.openstreetmap.josm.data.osm.Relation;
 import org.openstreetmap.josm.data.osm.Way;
@@ -560,5 +561,14 @@
 
     private static void waysToGpxData(Collection<Way> ways, GpxData gpxData, Set<Node> doneNodes) {
-        for (Way w : ways) {
+        /* When the dataset has been obtained from a gpx layer and now is being converted back,
+         * the ways have negative ids. The first created way corresponds to the first gpx segment,
+         * and has the highest id (i.e., closest to zero).
+         * Thus, sorting by OsmPrimitive#getUniqueId gives the original order.
+         * (Only works if the data layer has not been saved to and been loaded from an osm file before.)
+         */
+        final List<Way> sortedWays = new ArrayList<>(ways);
+        Collections.sort(sortedWays, new OsmPrimitiveComparator(true, false)); // sort by OsmPrimitive#getUniqueId ascending
+        Collections.reverse(sortedWays); // sort by OsmPrimitive#getUniqueId descending
+        for (Way w : sortedWays) {
             if (!w.isUsable()) {
                 continue;