diff --git a/Makefile.inc1 b/Makefile.inc1
index 989d016a5029..fbb451298f3c 100644
--- a/Makefile.inc1
+++ b/Makefile.inc1
@@ -120,7 +120,8 @@ SUPFLAGS+=	-h ${SUPHOST}
 
 MAKEOBJDIRPREFIX?=	/usr/obj
 .if !defined(OSRELDATE)
-OSRELDATE!=	sysctl -n kern.osreldate
+OSRELDATE!=	awk '/^\#define[[:space:]]*__FreeBSD_version/ { print $$3 }' \
+		/usr/include/osreldate.h
 .endif
 TARGET_ARCH?=	${MACHINE_ARCH}
 .if ${TARGET_ARCH} == ${MACHINE_ARCH}