diff --git a/node/IncomingPacket.cpp b/node/IncomingPacket.cpp
index 5fdcfc92f..a73ee1def 100644
--- a/node/IncomingPacket.cpp
+++ b/node/IncomingPacket.cpp
@@ -650,7 +650,7 @@ bool IncomingPacket::_doP5_MULTICAST_FRAME(const RuntimeEnvironment *RR,const Sh
 	}
 	return true;
 }
-#endif
+#endif // ZT_SUPPORT_LEGACY_MULTICAST
 
 bool IncomingPacket::_doMULTICAST_LIKE(const RuntimeEnvironment *RR,const SharedPtr<Peer> &peer)
 {