Index: trunk/test/unit/org/openstreetmap/josm/actions/JoinNodeWayActionTest.java
===================================================================
--- trunk/test/unit/org/openstreetmap/josm/actions/JoinNodeWayActionTest.java	(revision 16200)
+++ trunk/test/unit/org/openstreetmap/josm/actions/JoinNodeWayActionTest.java	(revision 16202)
@@ -17,4 +17,6 @@
 import org.openstreetmap.josm.data.osm.DataSet;
 import org.openstreetmap.josm.data.osm.Node;
+import org.openstreetmap.josm.data.osm.OsmPrimitiveType;
+import org.openstreetmap.josm.data.osm.SimplePrimitiveId;
 import org.openstreetmap.josm.data.osm.Way;
 import org.openstreetmap.josm.data.osm.visitor.BoundingXYVisitor;
@@ -213,3 +215,31 @@
     }
 
+    /**
+     * Non-regression test for <a href="https://josm.openstreetmap.de/ticket/18990">Bug #18990</a>.
+     * @throws Exception if an error occurs
+     */
+    @Test
+    public void testTicket18990() throws Exception {
+        DataSet ds = OsmReader.parseDataSet(TestUtils.getRegressionDataStream(18990, "18990-sample.osm"), null);
+        Layer layer = new OsmDataLayer(ds, OsmDataLayer.createNewName(), null);
+        MainApplication.getLayerManager().addLayer(layer);
+        try {
+            Node toMove = (Node) ds.getPrimitiveById(new SimplePrimitiveId(7018586511L, OsmPrimitiveType.NODE));
+            assertTrue(toMove != null);
+            Node expected = new Node(new LatLon(43.48582074476985, -96.76897750613033));
+
+            ds.setSelected(toMove);
+            setupMapView(ds);
+            JoinNodeWayAction action = JoinNodeWayAction.createMoveNodeOntoWayAction();
+            action.setEnabled(true);
+            action.actionPerformed(null);
+            assertTrue("Node was moved to an unexpected position", toMove.getEastNorth().equalsEpsilon(expected.getEastNorth(), 1e-7));
+            assertTrue("Node was not added to expected way", toMove.getParentWays().size() == 1);
+            assertTrue("Node was not added to expected way segment",
+                    toMove.getParentWays().iterator().next().getNodes().indexOf(toMove) == 2);
+        } finally {
+            MainApplication.getLayerManager().removeLayer(layer);
+        }
+    }
+
 }