diff --git a/loop/src/backbone.cc b/loop/src/backbone.cc
index 2445c55fc2b7a1554cf9bb3e35d87f70ba5f5f35..d59aac79df4296b95003efb21e4112b4055547f0 100644
--- a/loop/src/backbone.cc
+++ b/loop/src/backbone.cc
@@ -274,10 +274,8 @@ void BackboneList::InsertInto(ost::mol::ChainHandle& chain,
   ost::mol::ResNum n_num = start_resnum;
   ost::mol::ResNum c_num = start_resnum + this->size() -1;
 
-  ost::mol::ResidueHandle before = chain.FindResidue(n_num);
-  ost::mol::ResidueHandle after = chain.FindResidue(c_num);
-
   // handle n_stem
+  ost::mol::ResidueHandle before = chain.FindResidue(n_num);
   if (before.IsValid()) {
 
     ost::mol::AtomHandle n = before.FindAtom("N");
@@ -348,8 +346,9 @@ void BackboneList::InsertInto(ost::mol::ChainHandle& chain,
   }
 
   // handle c_stem
+  ost::mol::ResidueHandle after = chain.FindResidue(c_num);
   const uint last_idx = size() - 1;
-  if (after.IsValid()) {
+  if (n_num != c_num && after.IsValid()) {
 
     ost::mol::AtomHandle n = after.FindAtom("N");
     ost::mol::AtomHandle ca = after.FindAtom("CA");
@@ -390,7 +389,7 @@ void BackboneList::InsertInto(ost::mol::ChainHandle& chain,
     edi.RenameResidue(after, ost::conop::OneLetterCodeToResidueName(GetOLC(last_idx)));
     after.SetOneLetterCode(GetOLC(last_idx));
 
-  } else { // !after.IsValid()
+  } else if(n_num != c_num) { // !after.IsValid()
 
     after = edi.AppendResidue(chain, ost::conop::OneLetterCodeToResidueName(GetOLC(last_idx)), c_num);
     SetResidueProps(after, GetOLC(last_idx));