diff --git a/sys/modules/arcnet/Makefile b/sys/modules/arcnet/Makefile
index a4bac23f7d8..281793f9fcd 100644
--- a/sys/modules/arcnet/Makefile
+++ b/sys/modules/arcnet/Makefile
@@ -17,9 +17,12 @@ EXPORT_SYMS=	arc_frag_init	\
 		arc_storelladdr
 
 .if !defined(KERNBUILDDIR)
-opt_inet.h opt_inet6.h:
+opt_inet.h:
 	echo "#define INET 1" > ${.TARGET}
 
+opt_inet6.h:
+	echo "#define INET6 1" > ${.TARGET}
+
 opt_ipx.h:
 	echo "#define IPX 1" > ${.TARGET}
 .endif