Index: head/share/mk/src.sys.mk
===================================================================
--- head/share/mk/src.sys.mk	(revision 283766)
+++ head/share/mk/src.sys.mk	(revision 283767)
@@ -1,23 +1,26 @@
 # $FreeBSD$
 
 # Note: This file is also duplicated in the sys/conf/kern.pre.mk so
 # it will always grab SRCCONF, even if it isn't being built in-tree
 # to preserve historical (and useful) behavior. Changes here need to
 # be reflected there so SRCCONF isn't included multiple times.
 
+# make sure this is defined in a consistent manner
+SRCTOP:= ${.PARSEDIR:tA:H:H}
+
 # Allow user to configure things that only effect src tree builds.
 SRCCONF?=	/etc/src.conf
 .if (exists(${SRCCONF}) || ${SRCCONF} != "/etc/src.conf") && !target(_srcconf_included_)
-.include "${SRCCONF}"
+.sinclude "${SRCCONF}"
 _srcconf_included_:	.NOTMAIN
 .endif
-# If we were found via .../share/mk we need to replace that in
+# If we were found via .../share/mk we need to replace that
 # with ${.PARSEDIR:tA} so that we can be found by
 # sub-makes launched from objdir.
 .if ${.MAKEFLAGS:M.../share/mk} != ""
 .MAKEFLAGS:= ${.MAKEFLAGS:S,.../share/mk,${.PARSEDIR:tA},}
 .endif
 .if ${MAKESYSPATH:Uno:M*.../*} != ""
 MAKESYSPATH:= ${MAKESYSPATH:S,.../share/mk,${.PARSEDIR:tA},}
 .export MAKESYSPATH
 .endif