Index: head/net-mgmt/fastnetmon/Makefile
===================================================================
--- head/net-mgmt/fastnetmon/Makefile
+++ head/net-mgmt/fastnetmon/Makefile
@@ -30,6 +30,8 @@
 
 PORTDOCS=	*
 
+CFLAGS_i386=	-march=i586
+
 post-patch:
 	@${REINPLACE_CMD} -e 's|/usr/local|${LOCALBASE}|' ${WRKSRC}/src/CMakeLists.txt
 	@${REINPLACE_CMD} -e 's|/usr/local|${PREFIX}|; \