Index: /trunk/src/org/openstreetmap/josm/io/OsmJsonReader.java
===================================================================
--- /trunk/src/org/openstreetmap/josm/io/OsmJsonReader.java	(revision 17231)
+++ /trunk/src/org/openstreetmap/josm/io/OsmJsonReader.java	(revision 17232)
@@ -157,7 +157,10 @@
     private void readRelationMembersAndTags(JsonObject item, Relation r, Collection<RelationMemberData> members)
             throws IllegalDataException {
-        for (JsonValue v : item.getJsonArray("members")) {
-            JsonObject o = v.asJsonObject();
-            members.add(parseRelationMember(r, ((JsonNumber) o.get("ref")).longValue(), o.getString("type"), o.getString("role")));
+        JsonArray jsonArray = item.getJsonArray("members");
+        if (jsonArray != null) {
+            for (JsonValue v : jsonArray) {
+                JsonObject o = v.asJsonObject();
+                members.add(parseRelationMember(r, ((JsonNumber) o.get("ref")).longValue(), o.getString("type"), o.getString("role")));
+            }
         }
         readTags(item, r);
Index: /trunk/test/unit/org/openstreetmap/josm/io/OsmJsonReaderTest.java
===================================================================
--- /trunk/test/unit/org/openstreetmap/josm/io/OsmJsonReaderTest.java	(revision 17231)
+++ /trunk/test/unit/org/openstreetmap/josm/io/OsmJsonReaderTest.java	(revision 17232)
@@ -236,4 +236,21 @@
         assertTrue(r.isTagged());
         assertEquals("route", r.get("type"));
+
+    }
+
+    /**
+     * Test a relation example without members.
+     * @throws Exception never
+     */
+    @Test
+    public void testEmptyRelation() throws Exception {
+        DataSet ds = parse("{\n" +
+                "  \"type\": \"relation\",\n" +
+                "  \"id\": 1,\n" +
+                "  \"tags\": {}\n" +
+                "}");
+        Relation r = ds.getRelations().iterator().next();
+        assertEquals(1, r.getUniqueId());
+        assertEquals(0, r.getMembersCount());
     }