Index: applications/editors/josm/plugins/poly/src/poly/PolyExporter.java
===================================================================
--- applications/editors/josm/plugins/poly/src/poly/PolyExporter.java	(revision 34966)
+++ applications/editors/josm/plugins/poly/src/poly/PolyExporter.java	(revision 34991)
@@ -40,9 +40,9 @@
     public void exportData(File file, Layer layer) throws IOException {
         if (layer instanceof OsmDataLayer) {
-            if (((OsmDataLayer) layer).getDataSet().getWays().stream().anyMatch(w -> !w.isClosed())) {
+            DataSet ds = ((OsmDataLayer) layer).getDataSet();
+            if (ds.getWays().stream().anyMatch(w -> w.isUsable() && !w.isClosed())) {
                 throw new IOException(tr("Data contains unclosed ways."));
             }
             try (PrintWriter writer = new PrintWriter(Files.newBufferedWriter(file.toPath(), StandardCharsets.UTF_8))) {
-                DataSet ds = ((OsmDataLayer) layer).getDataSet();
                 HashSet<Way> written = new HashSet<>();
                 boolean firstFile = true;
@@ -54,5 +54,5 @@
 
                 for (Relation rel : ds.getRelations()) {
-                    if (rel.isMultipolygon()) {
+                    if (rel.isUsable() && rel.isMultipolygon()) {
                         if (!firstFile) {
                             writer.println();
@@ -68,5 +68,5 @@
                 int counter = 1;
                 for (Way w : ds.getWays()) {
-                    if (!written.contains(w)) {
+                    if (w.isUsable() && !written.contains(w)) {
                         writeWay(writer, w, counter);
                     }