diff --git a/src/hello-protocol.cpp b/src/hello-protocol.cpp
index 5e29223..b10afb0 100644
--- a/src/hello-protocol.cpp
+++ b/src/hello-protocol.cpp
@@ -45,6 +45,8 @@
                                        std::bind(&HelloProtocol::onContent,
                                                  this,
                                                  _1, _2),
+                                       std::bind(&HelloProtocol::processInterestTimedOut, // Nack
+                                                 this, _1),
                                        std::bind(&HelloProtocol::processInterestTimedOut,
                                                  this, _1));
 }
diff --git a/src/validator.hpp b/src/validator.hpp
index 04b2ea5..4387ea5 100644
--- a/src/validator.hpp
+++ b/src/validator.hpp
@@ -107,10 +107,14 @@
         // Attempt to fetch the certificate
         m_face->expressInterest(interest,
                                 std::bind(&Validator::onData, this, _1, _2, request),
+                                std::bind(&Validator::onTimeout, // Nack
+                                          this, _1, request->m_nRetries,
+                                          onFailure,
+                                          request),
                                 std::bind(&Validator::onTimeout,
-                                     this, _1, request->m_nRetries,
-                                     onFailure,
-                                     request));
+                                          this, _1, request->m_nRetries,
+                                          onFailure,
+                                          request));
       }
     }
   }