diff --git a/src/db/db/dbAsIfFlatRegion.cc b/src/db/db/dbAsIfFlatRegion.cc
index a62894e47..9005de616 100644
--- a/src/db/db/dbAsIfFlatRegion.cc
+++ b/src/db/db/dbAsIfFlatRegion.cc
@@ -1298,7 +1298,7 @@ AsIfFlatRegion::sized (coord_type dx, coord_type dy, unsigned int mode) const
 
     //  simplified handling for a box
     db::Box b = bbox ().enlarged (db::Vector (dx, dy));
-    return region_from_box (b, properties_repository (), begin ()->prop_id ());
+    return region_from_box (b, properties_repository (), db::RegionIterator (begin ()).prop_id ());
 
   } else if (! merged_semantics () || is_merged ()) {
 
@@ -1478,13 +1478,13 @@ AsIfFlatRegion::and_with (const Region &other, PropertyConstraint property_const
 
   } else if (is_box () && other.is_box ()) {
 
-    if (pc_skip (property_constraint) || pc_match (property_constraint, begin ()->prop_id (), other.begin ().prop_id ())) {
+    if (pc_skip (property_constraint) || pc_match (property_constraint, db::RegionIterator (begin ()).prop_id (), other.begin ().prop_id ())) {
 
       //  Simplified handling for boxes
       db::Box b = bbox ();
       b &= other.bbox ();
 
-      db::properties_id_type prop_id_out = pc_norm (property_constraint, begin ()->prop_id ());
+      db::properties_id_type prop_id_out = pc_norm (property_constraint, db::RegionIterator (begin ()).prop_id ());
 
       return region_from_box (b, properties_repository (), prop_id_out);
 
@@ -1494,7 +1494,7 @@ AsIfFlatRegion::and_with (const Region &other, PropertyConstraint property_const
 
   } else if (is_box () && ! other.strict_handling ()) {
 
-    db::properties_id_type self_prop_id = pc_skip (property_constraint) ? 0 : begin ()->prop_id ();
+    db::properties_id_type self_prop_id = pc_skip (property_constraint) ? 0 : db::RegionIterator (begin ()).prop_id ();
 
     //  map AND with box to clip ..
     db::Box b = bbox ();
diff --git a/src/db/db/dbDeepRegion.cc b/src/db/db/dbDeepRegion.cc
index 5acb010f8..b9b954408 100644
--- a/src/db/db/dbDeepRegion.cc
+++ b/src/db/db/dbDeepRegion.cc
@@ -784,7 +784,6 @@ RegionDelegate *
 DeepRegion::and_with (const Region &other, PropertyConstraint property_constraint) const
 {
   const DeepRegion *other_deep = dynamic_cast <const DeepRegion *> (other.delegate ());
-
   if (empty ()) {
 
     return clone ()->remove_properties (pc_remove (property_constraint));
diff --git a/src/db/db/dbGenericShapeIterator.h b/src/db/db/dbGenericShapeIterator.h
index c4abf65a7..0867dc009 100644
--- a/src/db/db/dbGenericShapeIterator.h
+++ b/src/db/db/dbGenericShapeIterator.h
@@ -31,6 +31,9 @@
 namespace db
 {
 
+template <class T>
+class generic_shape_iterator;
+
 template <class T>
 class DB_PUBLIC generic_shape_iterator_delegate_base
 {
@@ -40,6 +43,9 @@ class DB_PUBLIC generic_shape_iterator_delegate_base
   generic_shape_iterator_delegate_base () { }
   virtual ~generic_shape_iterator_delegate_base () { }
 
+protected:
+  friend class generic_shape_iterator<T>;
+
   virtual void do_reset (const db::Box & /*region*/, bool /*overlapping*/) { }
   virtual db::Box bbox () const { return db::Box::world (); }
   virtual bool is_addressable () const = 0;
@@ -62,6 +68,7 @@ class DB_PUBLIC generic_shape_iterator_delegate2
     : m_iter (from), m_from (from), m_to (to)
   { }
 
+protected:
   virtual bool is_addressable () const
   {
     return addressable;
@@ -122,6 +129,7 @@ class DB_PUBLIC generic_shape_iterator_delegate1
     : m_iter (from), m_from (from)
   { }
 
+protected:
   virtual bool is_addressable () const
   {
     return addressable;
@@ -185,6 +193,7 @@ class DB_PUBLIC generic_shapes_iterator_delegate
     set ();
   }
 
+protected:
   virtual bool is_addressable () const
   {
     return m_is_addressable;
diff --git a/testdata/ruby/dbRegionTest.rb b/testdata/ruby/dbRegionTest.rb
index 149c23171..a59478a11 100644
--- a/testdata/ruby/dbRegionTest.rb
+++ b/testdata/ruby/dbRegionTest.rb
@@ -1498,6 +1498,36 @@ def test_extended_iter
 
   end
 
+  # issue #1955 (locking of layout object inside DSS)
+  def test_issue1955
+
+    ly = RBA::Layout::new
+    top = ly.create_cell("TOP")
+    l1 = ly.layer(1, 0)
+
+    dss = RBA::DeepShapeStore::new
+
+    rr = RBA::Region::new(RBA::Box::new(100, 100, 1100, 1100))
+
+    r = RBA::Region::new(top.begin_shapes_rec(l1), dss)
+    r += RBA::Region::new(RBA::Box::new(0, 0, 1000, 1000))
+
+    # this spoils the dss object, if 
+    # 1. the first region is a deep region
+    # 2. the second region is a flat region
+    # 3. both regions are boxes
+    # after this operation, bounding boxes are no
+    # longer updated inside the DSS.
+    randrr = r & rr
+    assert_equal(randrr.to_s, "(100,100;100,1000;1000,1000;1000,100)")
+
+    r += RBA::Region::new(RBA::Box::new(1000, 1000, 2000, 2000))
+
+    assert_equal(r.to_s, "(0,0;0,1000;1000,1000;1000,0);(1000,1000;1000,2000;2000,2000;2000,1000)")
+    assert_equal(r.bbox.to_s, "(0,0;2000,2000)")
+
+  end
+
 end
 
 load("test_epilogue.rb")