diff --git a/src/util/command-interest-validator.hpp b/src/util/command-interest-validator.hpp
index af8c796..257f476 100644
--- a/src/util/command-interest-validator.hpp
+++ b/src/util/command-interest-validator.hpp
@@ -24,10 +24,11 @@
 
     GRACE_INTERVAL = 3000 // ms
   };
-  
-  CommandInterestValidator(int64_t graceInterval = GRACE_INTERVAL/*ms*/) 
+
+  CommandInterestValidator(const time::milliseconds& graceInterval = time::milliseconds(static_cast<int>(GRACE_INTERVAL)))
+    : m_graceInterval(graceInterval < time::milliseconds::zero() ?
+                      time::milliseconds(static_cast<int>(GRACE_INTERVAL)) : graceInterval)
   {
-    m_graceInterval = (graceInterval < 0 ? GRACE_INTERVAL : graceInterval);
   }
 
   virtual
@@ -43,26 +44,28 @@
 
 protected:
   virtual void
-  checkPolicy (const Data& data, 
-               int stepCount, 
-               const OnDataValidated &onValidated, 
+  checkPolicy (const Data& data,
+               int stepCount,
+               const OnDataValidated &onValidated,
                const OnDataValidationFailed &onValidationFailed,
                std::vector<shared_ptr<ValidationRequest> > &nextSteps)
   {
     onValidationFailed(data.shared_from_this(), "No policy for data checking");
   }
-  
+
   virtual void
-  checkPolicy (const Interest& interest, 
-               int stepCount, 
-               const OnInterestValidated &onValidated, 
+  checkPolicy (const Interest& interest,
+               int stepCount,
+               const OnInterestValidated &onValidated,
                const OnInterestValidationFailed &onValidationFailed,
                std::vector<shared_ptr<ValidationRequest> > &nextSteps);
 private:
-  int64_t m_graceInterval; //ms
+  time::milliseconds m_graceInterval; //ms
   std::map<Name, PublicKey> m_trustAnchorsForInterest;
   std::list<SecRuleSpecific> m_trustScopeForInterest;
-  std::map<Name, uint64_t> m_lastTimestamp;
+
+  typedef std::map<Name, time::system_clock::TimePoint> LastTimestampMap;
+  LastTimestampMap m_lastTimestamp;
 };
 
 inline void
@@ -82,28 +85,28 @@
 }
 
 inline void
-CommandInterestValidator::checkPolicy (const Interest& interest, 
-                                       int stepCount, 
-                                       const OnInterestValidated &onValidated, 
+CommandInterestValidator::checkPolicy (const Interest& interest,
+                                       int stepCount,
+                                       const OnInterestValidated &onValidated,
                                        const OnInterestValidationFailed &onValidationFailed,
                                        std::vector<shared_ptr<ValidationRequest> > &nextSteps)
 {
   const Name& interestName = interest.getName();
-  
-  //Prepare 
+
+  //Prepare
   if (interestName.size() < 4)
-    return onValidationFailed(interest.shared_from_this(), 
+    return onValidationFailed(interest.shared_from_this(),
                               "Interest is not signed: " + interest.getName().toUri());
-  
-  Signature signature(interestName[POS_SIG_INFO].blockFromValue(), 
+
+  Signature signature(interestName[POS_SIG_INFO].blockFromValue(),
                       interestName[POS_SIG_VALUE].blockFromValue());
-  
+
   SignatureSha256WithRsa sig(signature);
   const Name& keyLocatorName = sig.getKeyLocator().getName();
   Name keyName = IdentityCertificate::certificateNameToPublicKeyName(keyLocatorName);
-  
+
   //Check if command is in the trusted scope
-  bool inScope = false;  
+  bool inScope = false;
   for(std::list<SecRuleSpecific>::iterator scopeIt = m_trustScopeForInterest.begin();
       scopeIt != m_trustScopeForInterest.end();
       ++scopeIt)
@@ -115,23 +118,28 @@
         }
     }
   if(inScope == false)
-    return onValidationFailed(interest.shared_from_this(), 
+    return onValidationFailed(interest.shared_from_this(),
                               "Signer cannot be authorized for the command: " + keyName.toUri());
 
   //Check if timestamp is valid
-  uint64_t timestamp = interestName.get(POS_TIMESTAMP).toNumber();
-  uint64_t current = static_cast<uint64_t>(time::now()/1000000);
-  std::map<Name, uint64_t>::const_iterator timestampIt = m_lastTimestamp.find(keyName);
-  if(timestampIt == m_lastTimestamp.end())
+  time::system_clock::TimePoint interestTime = time::fromUnixTimestamp(
+                                           time::milliseconds(interestName.get(POS_TIMESTAMP).toNumber()));
+  time::system_clock::TimePoint currentTime = time::system_clock::now();
+
+  LastTimestampMap::iterator timestampIt = m_lastTimestamp.find(keyName);
+  if (timestampIt == m_lastTimestamp.end())
     {
-      if(timestamp > (current + m_graceInterval) || (timestamp + m_graceInterval) < current)
-        return onValidationFailed(interest.shared_from_this(), 
-                                  "The command is not in grace interval: " + interest.getName().toUri());
+      if (!(currentTime - m_graceInterval <= interestTime &&
+            interestTime <= currentTime + m_graceInterval))
+        {
+          return onValidationFailed(interest.shared_from_this(),
+                                    "The command is not in grace interval: " + interest.getName().toUri());
+        }
     }
-  else 
+  else
     {
-      if(m_lastTimestamp[keyName] >= timestamp)
-        return onValidationFailed(interest.shared_from_this(), 
+      if(interestTime <= timestampIt->second)
+        return onValidationFailed(interest.shared_from_this(),
                                   "The command is outdated: " + interest.getName().toUri());
     }
 
@@ -139,16 +147,22 @@
   if(!Validator::verifySignature(interestName.wireEncode().value(),
                                  interestName.wireEncode().value_size() - interestName[-1].size(),
                                  sig, m_trustAnchorsForInterest[keyName]))
-    return onValidationFailed(interest.shared_from_this(), 
+    return onValidationFailed(interest.shared_from_this(),
                               "Signature cannot be validated: " + interest.getName().toUri());
 
   //Update timestamp
-  m_lastTimestamp[keyName] = timestamp;
+  if (timestampIt == m_lastTimestamp.end())
+    {
+      m_lastTimestamp[keyName] = interestTime;
+    }
+  else
+    {
+      timestampIt->second = interestTime;
+    }
 
   return onValidated(interest.shared_from_this());
 }
 
-
 } // namespace ndn
 
 #endif // NDN_HELPERS_COMMAND_INTEREST_VALIDATOR_HPP