diff --git a/modules/mol/base/src/impl/chain_impl.hh b/modules/mol/base/src/impl/chain_impl.hh
index 018c3b9e1b76c8666f3593f2843fa9f63933ff9e..a2c607ec4e2df3cca3783a8a14532e795536593e 100644
--- a/modules/mol/base/src/impl/chain_impl.hh
+++ b/modules/mol/base/src/impl/chain_impl.hh
@@ -105,7 +105,9 @@ public:
 
   /// \brief append new residue with exactly the same parameters as res, but 
   ///     no atoms and bonds                               
-  ResidueImplPtr AppendResidue(const ResidueImplPtr& res, bool deep=true);
+  // force deep to be set explicitely, because it is better than implicit
+  // (and since we are on the impl level interface consistency isn't that critical)
+  ResidueImplPtr AppendResidue(const ResidueImplPtr& res, bool deep);
   
   ResidueImplPtr InsertResidueBefore(int index, const ResNum& n, 
                                      const ResidueKey& k);
diff --git a/modules/mol/base/src/impl/entity_impl.cc b/modules/mol/base/src/impl/entity_impl.cc
index 8b81293fbc01d47c81fa32af970b7d83c2075dcb..4b4cb3a7a1331b60d1295f0069a782b496503b72 100644
--- a/modules/mol/base/src/impl/entity_impl.cc
+++ b/modules/mol/base/src/impl/entity_impl.cc
@@ -145,13 +145,13 @@ void EntityImpl::ReplicateHierarchy(EntityImplPtr dest)
   for (ChainImplList::const_iterator i=chain_list_.begin(), 
        e1=chain_list_.end(); i!=e1; ++i) {
     ChainImplPtr src_chain=*i;
-    ChainImplPtr dst_chain=dest->InsertChain(src_chain);
+    ChainImplPtr dst_chain=dest->InsertChain(src_chain,false);
     // copy generic properties
     dst_chain->Assign(*src_chain.get());
     for (ResidueImplList::iterator j=src_chain->GetResidueList().begin(),
          e2=src_chain->GetResidueList().end(); j!=e2; ++j) {
       ResidueImplPtr src_res=*j;
-      ResidueImplPtr dst_res=dst_chain->AppendResidue(src_res);
+      ResidueImplPtr dst_res=dst_chain->AppendResidue(src_res, false);
       for (AtomImplList::iterator k=src_res->GetAtomList().begin(),
            e3=src_res->GetAtomList().end(); k!=e3; ++k) {
         AtomImplPtr src_atom=*k;
diff --git a/modules/mol/base/src/impl/entity_impl.hh b/modules/mol/base/src/impl/entity_impl.hh
index a5f5cd805cde4e67fb2ad33b4c376d65c4b2253a..c95bef408db5c911b40b71b6ae460baa5890b827 100644
--- a/modules/mol/base/src/impl/entity_impl.hh
+++ b/modules/mol/base/src/impl/entity_impl.hh
@@ -109,7 +109,9 @@ public:
   /// \brief insert a new chain based on parameters of the given chain
   /// 
   /// The chain will have no residues and atoms
-  ChainImplPtr InsertChain(const ChainImplPtr& chain, bool deep=false);
+  // force deep to be set explicitely, because it is better than implicit
+  // (and since we are on the impl level interface consistency isn't that critical)
+  ChainImplPtr InsertChain(const ChainImplPtr& chain, bool deep);
   ConnectorImplP Connect(const AtomImplPtr& first, const AtomImplPtr& second,
                          Real len, Real theta, Real phi,
                          unsigned char bond_order);
diff --git a/modules/mol/base/src/view_op.cc b/modules/mol/base/src/view_op.cc
index 6e4227e741d0faa02d5b1a902b1d63be0050aee2..6b8aebad85b78a9600e354b774cd512e990ccf54 100644
--- a/modules/mol/base/src/view_op.cc
+++ b/modules/mol/base/src/view_op.cc
@@ -296,7 +296,7 @@ public:
   
   virtual bool VisitResidue(const ResidueHandle& res)
   {
-    res_=chain_->AppendResidue(res.Impl());
+    res_=chain_->AppendResidue(res.Impl(),false);
     return true;
   }