diff --git a/bacnet-stack/lib/Makefile b/bacnet-stack/lib/Makefile
index 395ff91b..34f43546 100644
--- a/bacnet-stack/lib/Makefile
+++ b/bacnet-stack/lib/Makefile
@@ -12,6 +12,7 @@ LIBRARY = lib$(TARGET).a
 BACNET_DEFINES=-DPRINT_ENABLED=1 -DBACAPP_ALL -DBACFILE
 #BACDL_DEFINE=-DBACDL_ETHERNET=1
 #BACDL_DEFINE=-DBACDL_ARCNET=1
+#BACDL_DEFINE=-DBACDL_MSTP=1
 BACDL_DEFINE=-DBACDL_BIP=1
 DEFINES = $(BACNET_DEFINES) $(BACDL_DEFINE)
 # directories