diff --git a/protocol/ietf/CMakeLists.txt b/protocol/ietf/CMakeLists.txt
index fd7259b..752e550 100644
--- a/protocol/ietf/CMakeLists.txt
+++ b/protocol/ietf/CMakeLists.txt
@@ -1,2 +1,5 @@
 # RFC 4122 UUID
 add_subdirectory(uuid)
+
+# RFC 5905 NTPv4
+#add_subdirectory(ntp)