diff --git a/src/validator-panel.cpp b/src/validator-panel.cpp
index 8de4bb6..2197d66 100644
--- a/src/validator-panel.cpp
+++ b/src/validator-panel.cpp
@@ -14,12 +14,13 @@
 
 using namespace std;
 using namespace ndn;
-using namespace ndn::ptr_lib;
 
 INIT_LOGGER("ValidatorPanel");
 
 namespace chronos{
 
+using ndn::shared_ptr;
+
 const shared_ptr<CertificateCache> ValidatorPanel::DEFAULT_CERT_CACHE = shared_ptr<CertificateCache>();
 
 ValidatorPanel::ValidatorPanel(int stepLimit /* = 10 */,
@@ -39,7 +40,7 @@
                              int stepCount, 
                              const OnDataValidated& onValidated, 
                              const OnDataValidationFailed& onValidationFailed,
-                             vector<shared_ptr<ValidationRequest> >& nextSteps)
+                             std::vector<shared_ptr<ValidationRequest> >& nextSteps)
 {
   if(m_stepLimit == stepCount)
     {