diff --git a/src/plugins/streamers/lstream/db_plugin/lstrCompressor.h b/src/plugins/streamers/lstream/db_plugin/lstrCompressor.h
index 03e87b798..9e57d23a6 100644
--- a/src/plugins/streamers/lstream/db_plugin/lstrCompressor.h
+++ b/src/plugins/streamers/lstream/db_plugin/lstrCompressor.h
@@ -137,7 +137,7 @@ static inline db::Vector reduce_object (db::EdgePairWithProperties &ep)
  */
 static inline db::Vector reduce_object_point (db::Point &pt)
 {
-  db::Vector d = db::Point () - pt;
+  db::Vector d = db::Vector (pt);
   pt = db::Point ();
   return d;
 }
diff --git a/src/plugins/streamers/lstream/unit_tests/dbLStreamWriterTests.cc b/src/plugins/streamers/lstream/unit_tests/dbLStreamWriterTests.cc
new file mode 100644
index 000000000..b0f7b65a3
--- /dev/null
+++ b/src/plugins/streamers/lstream/unit_tests/dbLStreamWriterTests.cc
@@ -0,0 +1,153 @@
+
+/*
+
+  KLayout Layout Viewer
+  Copyright (C) 2006-2025 Matthias Koefferlein
+
+  This program is free software; you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation; either version 2 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program; if not, write to the Free Software
+  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+
+*/
+
+#include "lstrReader.h"
+#include "dbLayoutDiff.h"
+#include "dbWriter.h"
+#include "dbTestSupport.h"
+#include "tlUnitTest.h"
+
+#include <stdlib.h>
+
+static void run_test (tl::TestBase *_this, const std::string &base, const char *file, const char *file_au)
+{
+  db::LoadLayoutOptions options;
+
+  db::Manager m (false);
+  db::Layout layout (&m);
+
+  //  the reader is tested in the reader tests
+  {
+    std::string fn (base);
+    fn += "/lstream/";
+    fn += file;
+    tl::InputStream stream (fn);
+    db::Reader reader (stream);
+    reader.read (layout, options);
+  }
+
+  //  do a full spin
+
+  std::string tmp_file = _this->tmp_file ("tmp.lstr");
+
+  {
+    tl::OutputStream stream (tmp_file);
+    db::SaveLayoutOptions options;
+    options.set_format ("LStream");
+    db::Writer writer (options);
+    writer.write (layout, stream);
+  }
+
+  db::Layout layout_read (&m);
+  {
+    tl::InputStream file (tmp_file);
+    db::Reader reader (file);
+    reader.read (layout_read);
+  }
+
+  std::string fn_au (base);
+  fn_au += "/lstream/";
+  fn_au += file_au;
+
+  db::compare_layouts (_this, layout_read, fn_au, db::WriteOAS);
+}
+
+TEST(basic)
+{
+  run_test (_this, tl::testdata (), "basic.lstr", "basic_au.oas");
+}
+
+TEST(boxes)
+{
+  run_test (_this, tl::testdata (), "boxes.lstr", "boxes_au.oas");
+}
+
+TEST(cells)
+{
+  run_test (_this, tl::testdata (), "cells.lstr", "cells_au.oas");
+}
+
+TEST(cells_with_instances)
+{
+  run_test (_this, tl::testdata (), "cells_with_instances.lstr", "cells_with_instances_au.oas");
+}
+
+TEST(edge_pairs)
+{
+  run_test (_this, tl::testdata (), "edge_pairs.lstr", "edge_pairs_au.oas");
+}
+
+TEST(edges)
+{
+  run_test (_this, tl::testdata (), "edges.lstr", "edges_au.oas");
+}
+
+TEST(ghost_cells)
+{
+  run_test (_this, tl::testdata (), "ghost_cells.lstr", "ghost_cells_au.oas");
+}
+
+TEST(meta_data)
+{
+  run_test (_this, tl::testdata (), "meta_data.lstr", "meta_data_au.oas");
+}
+
+TEST(paths)
+{
+  run_test (_this, tl::testdata (), "paths.lstr", "paths_au.oas");
+}
+
+TEST(pcells)
+{
+  run_test (_this, tl::testdata (), "pcells.lstr", "pcells_au.oas");
+}
+
+TEST(points)
+{
+  run_test (_this, tl::testdata (), "points.lstr", "points_au.oas");
+}
+
+TEST(polygons)
+{
+  run_test (_this, tl::testdata (), "polygons.lstr", "polygons_au.oas");
+}
+
+TEST(properties)
+{
+  run_test (_this, tl::testdata (), "properties.lstr", "properties_au.oas");
+}
+
+TEST(simple_polygons)
+{
+  run_test (_this, tl::testdata (), "simple_polygons.lstr", "simple_polygons_au.oas");
+}
+
+TEST(texts)
+{
+  run_test (_this, tl::testdata (), "texts.lstr", "texts_au.oas");
+}
+
+TEST(variants)
+{
+  run_test (_this, tl::testdata (), "variants.lstr", "variants_au.oas");
+}
+
diff --git a/src/plugins/streamers/lstream/unit_tests/unit_tests.pro b/src/plugins/streamers/lstream/unit_tests/unit_tests.pro
index 8e83c6e61..5d192c4ef 100644
--- a/src/plugins/streamers/lstream/unit_tests/unit_tests.pro
+++ b/src/plugins/streamers/lstream/unit_tests/unit_tests.pro
@@ -7,7 +7,8 @@ include($$PWD/../lstream.pri)
 include($$PWD/../../../../lib_ut.pri)
 
 SOURCES = \
-  dbLStreamReaderTests.cc
+  dbLStreamReaderTests.cc \
+  dbLStreamWriterTests.cc
 
 INCLUDEPATH += $$LAY_INC $$TL_INC $$DB_INC $$GSI_INC $$PWD/../db_plugin $$PWD/../../../common $$PWD/../db_plugin/capnp
 DEPENDPATH += $$LAY_INC $$TL_INC $$DB_INC $$GSI_INC $$PWD/../db_plugin $$PWD/../../../common
diff --git a/testdata/lstream/points.lstr b/testdata/lstream/points.lstr
index ffc042f41..575bd9db0 100644
Binary files a/testdata/lstream/points.lstr and b/testdata/lstream/points.lstr differ
diff --git a/testdata/lstream/points_au.oas b/testdata/lstream/points_au.oas
index 97b971d27..4724ea73f 100644
Binary files a/testdata/lstream/points_au.oas and b/testdata/lstream/points_au.oas differ