diff --git a/src/db/db/dbRecursiveInstanceIterator.cc b/src/db/db/dbRecursiveInstanceIterator.cc
index 257d49550..60577cf67 100644
--- a/src/db/db/dbRecursiveInstanceIterator.cc
+++ b/src/db/db/dbRecursiveInstanceIterator.cc
@@ -83,7 +83,6 @@ RecursiveInstanceIterator &RecursiveInstanceIterator::operator= (const Recursive
 RecursiveInstanceIterator::RecursiveInstanceIterator ()
 {
   //  anything. Not necessary reasonable.
-  mp_layout = 0;
   mp_top_cell = 0;
   mp_cell = 0;
   m_overlapping = false;
@@ -97,7 +96,7 @@ RecursiveInstanceIterator::RecursiveInstanceIterator ()
 RecursiveInstanceIterator::RecursiveInstanceIterator (const layout_type &layout, const cell_type &cell, const box_type &region, bool overlapping)
   : m_box_convert (layout)
 {
-  mp_layout = &layout;
+  mp_layout = const_cast<db::Layout *> (&layout);
   mp_top_cell = &cell;
   m_overlapping = overlapping;
   init ();
@@ -107,7 +106,7 @@ RecursiveInstanceIterator::RecursiveInstanceIterator (const layout_type &layout,
 RecursiveInstanceIterator::RecursiveInstanceIterator (const layout_type &layout, const cell_type &cell, const region_type &region, bool overlapping)
   : m_box_convert (layout)
 {
-  mp_layout = &layout;
+  mp_layout = const_cast<db::Layout *> (&layout);
   mp_top_cell = &cell;
   m_overlapping = overlapping;
   init ();
@@ -117,7 +116,7 @@ RecursiveInstanceIterator::RecursiveInstanceIterator (const layout_type &layout,
 RecursiveInstanceIterator::RecursiveInstanceIterator (const layout_type &layout, const cell_type &cell)
   : m_box_convert (layout)
 {
-  mp_layout = &layout;
+  mp_layout = const_cast<db::Layout *> (&layout);
   mp_top_cell = &cell;
   m_overlapping = false;
   init ();
@@ -272,6 +271,7 @@ RecursiveInstanceIterator::validate (RecursiveInstanceReceiver *receiver) const
   m_inst_array_iterators.clear ();
   m_cells.clear ();
   m_trans = cplx_trans_type ();
+  m_target_tree.clear ();
 
   m_local_region_stack.clear ();
   m_local_region_stack.push_back (m_region);
@@ -300,10 +300,9 @@ RecursiveInstanceIterator::validate (RecursiveInstanceReceiver *receiver) const
 
   }
 
-  if (mp_top_cell) {
+  if (mp_top_cell && mp_layout) {
 
     if (! m_all_targets) {
-      m_target_tree.clear ();
       mp_top_cell->collect_called_cells (m_target_tree);
     }
 
@@ -501,6 +500,8 @@ RecursiveInstanceIterator::next_instance (RecursiveInstanceReceiver *receiver) c
 void
 RecursiveInstanceIterator::down (RecursiveInstanceReceiver *receiver) const
 {
+  tl_assert (mp_layout);
+
   m_trans_stack.push_back (m_trans);
   m_cells.push_back (mp_cell);
 
diff --git a/src/db/db/dbRecursiveInstanceIterator.h b/src/db/db/dbRecursiveInstanceIterator.h
index 7f1f671b3..29fafcdda 100644
--- a/src/db/db/dbRecursiveInstanceIterator.h
+++ b/src/db/db/dbRecursiveInstanceIterator.h
@@ -29,6 +29,7 @@
 #include "dbLayout.h"
 #include "dbInstElement.h"
 #include "tlAssert.h"
+#include "tlObject.h"
 
 #include <map>
 #include <set>
@@ -180,7 +181,7 @@ public:
    */
   const layout_type *layout () const
   {
-    return mp_layout;
+    return mp_layout.get ();
   }
 
   /**
@@ -544,7 +545,7 @@ private:
   std::set<db::cell_index_type> m_targets;
   bool m_all_targets;
 
-  const layout_type *mp_layout;
+  tl::weak_ptr<layout_type> mp_layout;
   const cell_type *mp_top_cell;
 
   box_type m_region;
diff --git a/src/db/unit_tests/dbRecursiveInstanceIteratorTests.cc b/src/db/unit_tests/dbRecursiveInstanceIteratorTests.cc
index e8ba49cea..6656613c7 100644
--- a/src/db/unit_tests/dbRecursiveInstanceIteratorTests.cc
+++ b/src/db/unit_tests/dbRecursiveInstanceIteratorTests.cc
@@ -619,3 +619,44 @@ TEST(4)
   EXPECT_EQ (db::compare_layouts (boxes2layout (selected_boxes), boxes2layout (selected_boxes2), db::layout_diff::f_verbose, 0, 100 /*max diff lines*/), true);
 }
 
+TEST(5)
+{
+  std::unique_ptr<db::Layout> g (new db::Layout ());
+  g->insert_layer (0);
+  g->insert_layer (1);
+  g->insert_layer (2);
+
+  db::Cell &c0 (g->cell (g->add_cell ()));
+  db::Cell &c1 (g->cell (g->add_cell ()));
+  db::Cell &c2 (g->cell (g->add_cell ()));
+  db::Cell &c3 (g->cell (g->add_cell ()));
+
+  db::Box b (0, 100, 1000, 1200);
+  c0.shapes (0).insert (b);
+  c1.shapes (0).insert (b);
+  c2.shapes (0).insert (b);
+  c3.shapes (0).insert (b);
+
+  c0.shapes (2).insert (b);
+  c0.shapes (2).insert (b.moved (db::Vector (50, 50)));
+
+  db::Trans tt;
+  c0.insert (db::CellInstArray (db::CellInst (c1.cell_index ()), tt));
+  c0.insert (db::CellInstArray (db::CellInst (c2.cell_index ()), db::Trans (db::Vector (100, -100))));
+  c0.insert (db::CellInstArray (db::CellInst (c3.cell_index ()), db::Trans (1)));
+  c2.insert (db::CellInstArray (db::CellInst (c3.cell_index ()), db::Trans (db::Vector (1100, 0))));
+
+  std::string x;
+
+  db::RecursiveInstanceIterator i1 (*g, c0, db::Box (0, 0, 100, 100));
+  x = collect(i1, *g);
+  EXPECT_EQ (x, "[$1]$2 r0 0,0/[$1]$3 r0 100,-100");
+
+  g.reset (new db::Layout ());
+
+  //  now the layout is gone and the iterator stays silent (weak pointer to layout)
+  //  NOTE: this only works on reset or re-initialization. Not during iteration.
+  i1.reset ();
+  x = collect(i1, *g);
+  EXPECT_EQ (x, "");
+}