diff --git a/src/update/prefix-update-processor.hpp b/src/update/prefix-update-processor.hpp
index 6dc6c09..395d161 100644
--- a/src/update/prefix-update-processor.hpp
+++ b/src/update/prefix-update-processor.hpp
@@ -78,11 +78,20 @@
   void
   startListening();
 
+  void
+  enable()
+  {
+    m_isEnabled = true;
+  }
+
 private:
   void
   onInterest(const ndn::Interest& request);
 
   void
+  sendNack(const ndn::Interest& request);
+
+  void
   sendResponse(const std::shared_ptr<const ndn::Interest>& request,
                uint32_t code,
                const std::string& text);
@@ -128,6 +137,7 @@
   SyncLogicHandler& m_sync;
   ndn::KeyChain& m_keyChain;
   Validator m_validator;
+  bool m_isEnabled;
 
   const ndn::Name COMMAND_PREFIX; // /localhost/nlsr/prefix-update