diff --git a/modules/mol/base/src/impl/residue_impl.cc b/modules/mol/base/src/impl/residue_impl.cc
index 8a92cb01e83638f40d30f73536fade13e29141fd..75590b1fea096169c76226df15442543fafd697e 100644
--- a/modules/mol/base/src/impl/residue_impl.cc
+++ b/modules/mol/base/src/impl/residue_impl.cc
@@ -390,7 +390,7 @@ void ResidueImpl::DeleteAllAtoms() {
 
 String ResidueImpl::GetQualifiedName() const {
   String chain_name=this->GetChain()->GetName();
-  return (chain_name==" " ? "" :  chain_name+".")+
+  return ((chain_name==" " || chain_name=="") ? "" :  chain_name+".")+
          this->GetKey()+
          this->GetNumber().AsString();
 }