diff --git a/net/ntraceroute/Makefile b/net/ntraceroute/Makefile
index f54f8ccf4802..a23d64101aeb 100644
--- a/net/ntraceroute/Makefile
+++ b/net/ntraceroute/Makefile
@@ -24,7 +24,7 @@ PLIST_FILES=	sbin/${PORTNAME}
 
 .include <bsd.port.pre.mk>
 
-.if ${OSVERSION} >= 1100030
+.if ${OPSYS} == FreeBSD && ${OSVERSION} >= 1100030
 BUILD_FLAGS=	-DBYTESWAP_IP_FLAGS -DBYTESWAP_IP_LEN
 .endif