diff --git a/src/encoding/der/visitor/certificate-data-visitor.cpp b/src/encoding/der/visitor/certificate-data-visitor.cpp
index 4270d68..7edf794 100644
--- a/src/encoding/der/visitor/certificate-data-visitor.cpp
+++ b/src/encoding/der/visitor/certificate-data-visitor.cpp
@@ -18,7 +18,6 @@
 #include "certificate-data-visitor.hpp"
 
 using namespace std;
-using namespace ndn::ptr_lib;
 
 INIT_LOGGER("ndn.der.CertificateDataVisitor");
 
@@ -41,7 +40,7 @@
   children[1]->accept(subjectVisitor, param);
   PublicKeyVisitor pubkeyVisitor;
   Certificate* certData = ndnboost::any_cast<Certificate*>(param);
-  certData->setPublicKeyInfo(*ndnboost::any_cast<shared_ptr<PublicKey> >(children[2]->accept(pubkeyVisitor)));
+  certData->setPublicKeyInfo(*ndnboost::any_cast<ptr_lib::shared_ptr<PublicKey> >(children[2]->accept(pubkeyVisitor)));
       
   if(children.size() > 3)
     {
diff --git a/src/encoding/der/visitor/public-key-visitor.cpp b/src/encoding/der/visitor/public-key-visitor.cpp
index a2eab56..a5f5542 100644
--- a/src/encoding/der/visitor/public-key-visitor.cpp
+++ b/src/encoding/der/visitor/public-key-visitor.cpp
@@ -12,7 +12,6 @@
 #include "public-key-visitor.hpp"
 
 using namespace std;
-using namespace ndn::ptr_lib;
 
 namespace ndn {
 
@@ -24,10 +23,10 @@
   DerNodePtrList& children = derSeq.getChildren();
 
   SimpleVisitor simpleVisitor;
-  shared_ptr<DerSequence> algoSeq = dynamic_pointer_cast<DerSequence>(children[0]); 
+  ptr_lib::shared_ptr<DerSequence> algoSeq = ptr_lib::dynamic_pointer_cast<DerSequence>(children[0]); 
   OID algorithm = ndnboost::any_cast<OID>(algoSeq->getChildren()[0]->accept(simpleVisitor));  
   Blob raw = derSeq.getRaw();   
-  return ndnboost::any(shared_ptr<PublicKey>(new PublicKey(algorithm, raw)));    
+  return ndnboost::any(ptr_lib::shared_ptr<PublicKey>(new PublicKey(algorithm, raw)));    
 }
 
 } // der