diff --git a/src/db/unit_tests/dbLibrariesTests.cc b/src/db/unit_tests/dbLibrariesTests.cc
index 971f0df6f..b7730a7d0 100644
--- a/src/db/unit_tests/dbLibrariesTests.cc
+++ b/src/db/unit_tests/dbLibrariesTests.cc
@@ -619,59 +619,84 @@ TEST(3)
 
 TEST(4)
 {
-  LIBT_A *lib_a1 = new LIBT_A ();
+  tl::weak_ptr<LIBT_A> lib_a1 (new LIBT_A ());
   lib_a1->add_technology ("X");
-  db::LibraryManager::instance ().register_lib (lib_a1);
 
-  EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A").first, true);
-  EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A").second, lib_a1->get_id ());
-  EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "Z").first, false);
-  EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "").first, true);
-  EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "").second, lib_a1->get_id ());
-  EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "X").first, true);
-  EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "X").second, lib_a1->get_id ());
-
-  LIBT_A *lib_a2 = new LIBT_A ();
+  tl::weak_ptr<LIBT_A> lib_a2 (new LIBT_A ());
   lib_a2->add_technology ("Y");
-  db::LibraryManager::instance ().register_lib (lib_a2);
 
-  EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A").first, true);
-  EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A").second, lib_a2->get_id ());
-  EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "Z").first, false);
-  EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "").first, true);
-  EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "").second, lib_a2->get_id ());
-  EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "X").first, true);
-  EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "X").second, lib_a1->get_id ());
-  EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "Y").first, true);
-  EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "Y").second, lib_a2->get_id ());
-
-  LIBT_A *lib_a3 = new LIBT_A ();
+  tl::weak_ptr<LIBT_A> lib_a3 (new LIBT_A ());
   lib_a3->add_technology ("X");
-  db::LibraryManager::instance ().register_lib (lib_a3);
 
-  EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A").first, true);
-  EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A").second, lib_a3->get_id ());
-  EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "Z").first, false);
-  EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "").first, true);
-  EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "").second, lib_a3->get_id ());
-  EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "X").first, true);
-  EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "X").second, lib_a3->get_id ());
-  EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "Y").first, true);
-  EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "Y").second, lib_a2->get_id ());
+  tl::weak_ptr<LIBT_A> lib_a4 (new LIBT_A ());
 
+  try {
 
-  LIBT_A *lib_a4 = new LIBT_A ();
-  db::LibraryManager::instance ().register_lib (lib_a4);
+    EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A").first, false);
+    EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "Z").first, false);
+    EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "").first, false);
+    EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "X").first, false);
 
-  EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A").first, true);
-  EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A").second, lib_a3->get_id ());
-  EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "Z").first, true);
-  EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "Z").second, lib_a4->get_id ());
-  EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "").first, true);
-  EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "").second, lib_a3->get_id ());
-  EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "X").first, true);
-  EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "X").second, lib_a3->get_id ());
-  EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "Y").first, true);
-  EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "Y").second, lib_a2->get_id ());
+    db::LibraryManager::instance ().register_lib (lib_a1.get ());
+
+    EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A").first, false);
+    EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "Z").first, false);
+    EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "").first, false);
+    EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "X").first, true);
+    EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "X").second, lib_a1->get_id ());
+
+    db::LibraryManager::instance ().register_lib (lib_a2.get ());
+
+    EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A").first, false);
+    EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "Z").first, false);
+    EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "").first, false);
+    EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "X").first, true);
+    EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "X").second, lib_a1->get_id ());
+    EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "Y").first, true);
+    EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "Y").second, lib_a2->get_id ());
+
+    db::LibraryManager::instance ().register_lib (lib_a3.get ());
+    //  lib_a3 replaces lib_a1
+    EXPECT_EQ (lib_a1.get () == 0, true);
+
+    EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A").first, false);
+    EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "Z").first, false);
+    EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "").first, false);
+    EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "X").first, true);
+    EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "X").second, lib_a3->get_id ());
+    EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "Y").first, true);
+    EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "Y").second, lib_a2->get_id ());
+
+    db::LibraryManager::instance ().register_lib (lib_a4.get ());
+
+    EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A").first, true);
+    EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A").second, lib_a4->get_id ());
+    EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "Z").first, true);
+    EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "Z").second, lib_a4->get_id ());
+    EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "").first, true);
+    EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "").second, lib_a4->get_id ());
+    EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "X").first, true);
+    EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "X").second, lib_a3->get_id ());
+    EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "Y").first, true);
+    EXPECT_EQ (db::LibraryManager::instance ().lib_by_name ("A", "Y").second, lib_a2->get_id ());
+
+    //  because we switch to editable mode in between we have to clear the repository explicitly. Otherwise it's being cleared
+    //  on next entry of TEST which will cause a segmentation fault if editable mode is different then.
+    if (lib_a1.get ()) { db::LibraryManager::instance ().delete_lib (lib_a1.get ()); }
+    if (lib_a2.get ()) { db::LibraryManager::instance ().delete_lib (lib_a2.get ()); }
+    if (lib_a3.get ()) { db::LibraryManager::instance ().delete_lib (lib_a3.get ()); }
+    if (lib_a4.get ()) { db::LibraryManager::instance ().delete_lib (lib_a4.get ()); }
+
+  } catch (...) {
+
+    //  because we switch to editable mode in between we have to clear the repository explicitly. Otherwise it's being cleared
+    //  on next entry of TEST which will cause a segmentation fault if editable mode is different then.
+    if (lib_a1.get ()) { db::LibraryManager::instance ().delete_lib (lib_a1.get ()); }
+    if (lib_a2.get ()) { db::LibraryManager::instance ().delete_lib (lib_a2.get ()); }
+    if (lib_a3.get ()) { db::LibraryManager::instance ().delete_lib (lib_a3.get ()); }
+    if (lib_a4.get ()) { db::LibraryManager::instance ().delete_lib (lib_a4.get ()); }
+    throw;
+
+  }
 }
 
diff --git a/src/plugins/streamers/magic/db_plugin/dbMAGReader.cc b/src/plugins/streamers/magic/db_plugin/dbMAGReader.cc
index 23c7d3678..29bb3fe1d 100644
--- a/src/plugins/streamers/magic/db_plugin/dbMAGReader.cc
+++ b/src/plugins/streamers/magic/db_plugin/dbMAGReader.cc
@@ -72,7 +72,7 @@ MAGReader::read (db::Layout &layout)
 const LayerMap &
 MAGReader::read (db::Layout &layout, const db::LoadLayoutOptions &options)
 {
-  prepare_layers ();
+  prepare_layers (layout);
 
   mp_klayout_tech = layout.technology ();