diff --git a/libexec/telnetd/Makefile b/libexec/telnetd/Makefile
index 11f4b0c12d75..4281db8cb9c3 100644
--- a/libexec/telnetd/Makefile
+++ b/libexec/telnetd/Makefile
@@ -14,13 +14,17 @@ MAN=		telnetd.8
 SRCS=		global.c slc.c state.c sys_term.c telnetd.c \
 		termstat.c utility.c
 
-CFLAGS+=	-DLINEMODE -DUSE_TERMIO -DDIAGNOSTICS -DOLD_ENVIRON \
-		-DENV_HACK \
-		-I${TELNETDIR} -DINET6
-
 WARNS?=		2
 WFORMAT?=	0
 
+CFLAGS+=	-DLINEMODE -DUSE_TERMIO -DDIAGNOSTICS -DOLD_ENVIRON -DENV_HACK
+
+.if ${MK_INET6_SUPPORT} != "no"
+CFLAGS+=	-DINET6
+.endif
+
+CFLAGS+=	-I${TELNETDIR}
+
 LIBTELNET=	${.OBJDIR}/../../lib/libtelnet/libtelnet.a
 
 DPADD=		${LIBUTIL} ${LIBTERMCAP} ${LIBTELNET}