diff --git a/src/db/db/dbHierNetworkProcessor.cc b/src/db/db/dbHierNetworkProcessor.cc
index 256e87ad7..07166fa44 100644
--- a/src/db/db/dbHierNetworkProcessor.cc
+++ b/src/db/db/dbHierNetworkProcessor.cc
@@ -1581,6 +1581,10 @@ template <class T>
 void
 connected_clusters<T>::rename_connection (const ClusterInstance &inst, typename local_cluster<T>::id_type to_id)
 {
+  if (inst.id () == to_id) {
+    return;  //  nothing to do
+  }
+
   ClusterInstance new_inst (to_id, inst);
 
   auto rc = m_rev_connections.find (inst);
@@ -1589,24 +1593,48 @@ connected_clusters<T>::rename_connection (const ClusterInstance &inst, typename
   }
 
   auto id = rc->second;
-
-  //  TODO: this linear search may be slow
-  auto &connections = m_connections [id];
-  for (auto i = connections.begin (); i != connections.end (); ++i) {
-    if (*i == inst) {
-      *i = new_inst;
-      break;
-    }
-  }
-
   m_rev_connections.erase (rc);
 
-  //  NOTE: if a connection to the new cluster already exists, we will not insert here.
-  //  This may mean we are connecting two clusters here on parent level. In the netlist, this
-  //  is reflected by having multiple upward pins. Right now, we cannot reflect this case
-  //  in the reverse connection structures and keep the first one only in the reverse
-  //  lookup.
-  m_rev_connections.insert (std::make_pair (new_inst, id));
+  auto &connections = m_connections [id];
+
+  auto rc_exists = m_rev_connections.find (new_inst);
+  if (rc_exists != m_rev_connections.end ()) {
+
+    //  NOTE: possibly a different connection to the new cluster already exists (i.e.
+    //  rc_exists->second != id).
+    //  This may mean we are connecting two clusters here on parent level. In the netlist, this
+    //  is reflected by having multiple upward pins. Right now, we cannot reflect this case
+    //  in the reverse connection structures and keep the existing one only in the reverse
+    //  lookup.
+
+    //  Remove to original connections downwards
+    //  TODO: this linear search may be slow
+    for (auto i = connections.begin (), ii = connections.begin (); i != connections.end (); ii = i, ++i) {
+      if (*i == inst) {
+        if (ii == i) {
+          connections.pop_front ();
+        } else {
+          connections.erase_after (ii);
+        }
+        break;
+      }
+    }
+
+  } else {
+
+    m_rev_connections.insert (std::make_pair (new_inst, id));
+
+    //  Replace connections downwards
+    //  TODO: this linear search may be slow
+    for (auto i = connections.begin (); i != connections.end (); ++i) {
+      if (*i == inst) {
+        *i = new_inst;
+        break;
+      }
+    }
+
+  }
+
 }
 
 template <class T>
@@ -1627,7 +1655,7 @@ connected_clusters<T>::join_cluster_with (typename local_cluster<T>::id_type id,
     connections_type &to_join = tc->second;
 
     for (connections_type::const_iterator c = to_join.begin (); c != to_join.end (); ++c) {
-      m_rev_connections.insert (std::make_pair (*c, id));
+      m_rev_connections [*c] = id;
     }
 
     connections_type &target = m_connections [id];
diff --git a/src/db/db/dbLayoutToNetlist.cc b/src/db/db/dbLayoutToNetlist.cc
index 9ca1c1f9f..db8e9d146 100644
--- a/src/db/db/dbLayoutToNetlist.cc
+++ b/src/db/db/dbLayoutToNetlist.cc
@@ -212,7 +212,7 @@ void LayoutToNetlist::link_nets (const db::Net *net, const db::Net *with)
 {
   if (! net->circuit () || net->circuit () != with->circuit () || ! internal_layout ()
       || ! internal_layout ()->is_valid_cell_index (net->circuit ()->cell_index ())
-      || net->cluster_id () == 0 || with->cluster_id () == 0) {
+      || net->cluster_id () == 0 || with->cluster_id () == 0 || net == with) {
     return;
   }
 
diff --git a/src/tl/tl/tlSList.h b/src/tl/tl/tlSList.h
index a5412e40a..b387f9e57 100644
--- a/src/tl/tl/tlSList.h
+++ b/src/tl/tl/tlSList.h
@@ -46,6 +46,8 @@ namespace tl
  *  - empty
  */
 
+template <class T> class slist;
+
 template <class T>
 struct slist_node_type
 {
@@ -87,6 +89,7 @@ public:
 
 private:
   friend class slist_const_iterator<T>;
+  friend class slist<T>;
   node_type *mp_p;
 };
 
@@ -119,6 +122,7 @@ public:
   bool operator!= (slist_const_iterator<T> other) const { return mp_p != other.mp_p; }
 
 private:
+  friend class slist<T>;
   const node_type *mp_p;
 };
 
@@ -304,6 +308,15 @@ public:
     other.m_size = 0;
   }
 
+  void erase_after (iterator at)
+  {
+    node_type *n = at.mp_p->next;
+    if (n) {
+      at.mp_p->next = n->next;
+      delete n;
+    }
+  }
+
 private:
   node_type *mp_first, *mp_last;
   size_t m_size;
diff --git a/src/tl/unit_tests/tlSListTests.cc b/src/tl/unit_tests/tlSListTests.cc
index 78b94df80..636f70028 100644
--- a/src/tl/unit_tests/tlSListTests.cc
+++ b/src/tl/unit_tests/tlSListTests.cc
@@ -105,6 +105,16 @@ TEST(1_Basic)
     EXPECT_EQ (l2s (l2), "17,42");
     l2.pop_front ();
     EXPECT_EQ (l2s (l2), "42");
+    l2.push_front (MyClass1 (11));
+    EXPECT_EQ (l2s (l2), "11,42");
+    l2.erase_after (l2.begin ());
+    EXPECT_EQ (l2s (l2), "11");
+    l2.erase_after (l2.begin ());  //  ignored
+    EXPECT_EQ (l2s (l2), "11");
+    l2.pop_front ();
+    EXPECT_EQ (l2s (l2), "");
+    EXPECT_EQ (l2.empty (), true);
+    l2.push_front (MyClass1 (42));
 
     l3.push_back (MyClass1 (2));
     l3.push_front (MyClass1 (1));