diff --git a/src/chatroom-info.cpp b/src/chatroom-info.cpp
index f6b81e3..9dc3439 100644
--- a/src/chatroom-info.cpp
+++ b/src/chatroom-info.cpp
@@ -72,7 +72,7 @@
   totalLength += block.prependVarNumber(tlv::ChatroomPrefix);
 
   // Trust Model
-  totalLength += prependNonNegativeIntegerBlock(block, tlv::TrustModel, m_trustModel);
+  totalLength += ndn::prependNonNegativeIntegerBlock(block, tlv::TrustModel, m_trustModel);
 
   // Chatroom Name
   size_t chatroomNameLength = m_chatroomName.wireEncode(block);