diff --git a/Makefile.inc1 b/Makefile.inc1
index 2b8f46b3679a..242e76b24e18 100644
--- a/Makefile.inc1
+++ b/Makefile.inc1
@@ -563,7 +563,8 @@ KTMAKE=		TOOLS_PREFIX=${WORLDTMP} MAKEOBJDIRPREFIX=${WORLDTMP} \
 # world stage
 WMAKEENV=	${CROSSENV} \
 		INSTALL="sh ${.CURDIR}/tools/install.sh" \
-		PATH=${TMPPATH}
+		PATH=${TMPPATH} \
+		SYSROOT=${WORLDTMP}
 
 # make hierarchy
 HMAKE=		PATH=${TMPPATH} ${MAKE} LOCAL_MTREE=${LOCAL_MTREE:Q}
@@ -722,7 +723,7 @@ IMAKE_MTREE=	MTREE_CMD="mtree ${MTREEFLAGS}"
 .endif
 
 # kernel stage
-KMAKEENV=	${WMAKEENV}
+KMAKEENV=	${WMAKEENV:NSYSROOT=*}
 KMAKE=		${KMAKEENV} ${MAKE} ${.MAKEFLAGS} ${KERNEL_FLAGS} KERNEL=${INSTKERNNAME}
 
 #
diff --git a/Makefile.libcompat b/Makefile.libcompat
index 2e075ff098f6..3c0aabb2d05f 100644
--- a/Makefile.libcompat
+++ b/Makefile.libcompat
@@ -111,6 +111,7 @@ LIBCOMPATCXXFLAGS+=	-isystem ${LIBCOMPATTMP}/usr/include/c++/v1 -std=c++11 \
 LIBCOMPATWMAKEENV+= MAKEOBJDIRPREFIX=${LIBCOMPAT_OBJTREE} \
 		INSTALL="sh ${.CURDIR}/tools/install.sh" \
 		PATH=${TMPPATH} \
+		SYSROOT=${LIBCOMPATTMP} \
 		LIBDIR=/usr/lib${libcompat} \
 		SHLIBDIR=/usr/lib${libcompat} \
 		DTRACE="${LIB$COMPATDTRACE:U${DTRACE}}"