diff --git a/tools/build/Makefile b/tools/build/Makefile
--- a/tools/build/Makefile
+++ b/tools/build/Makefile
@@ -351,10 +351,12 @@
 MSDOSFSINCS+=	${SRCTOP}/sys/fs/msdosfs/msdosfsmount.h
 DISKINCS+=	${SRCTOP}/sys/sys/disk/bsd.h
 
+.if ${.MAKE.OS} == "FreeBSD"
 # Needed to build most of the things below, which include sys/cdefs.h either
 # directly or transitively
 SYSINCS+=	${SRCTOP}/sys/sys/_visible.h
 SYSINCS+=	${SRCTOP}/sys/sys/cdefs.h
+.endif
 
 # Needed to build config (since it uses libnv)
 SYSINCS+=	${SRCTOP}/sys/sys/_nv.h