--- Makefile.inc1
+++ Makefile.inc1
@@ -191,7 +191,9 @@ TMPPATH=	${STRICTTMPPATH}:${PATH}
 # when in the middle of installing over this system.
 #
 .if make(distributeworld) || make(installworld)
-INSTALLTMP!=	/usr/bin/mktemp -d -u -t install
+INSTALLTMPDIR=	${OBJTREE}${.CURDIR}/itmp
+INSTALLTMP!=	/bin/mkdir -p ${INSTALLTMPDIR} && /usr/bin/env \
+		TMPDIR=${INSTALLTMPDIR} /usr/bin/mktemp -d -u -t install
 .endif
 
 #
@@ -833,7 +835,7 @@ distributeworld installworld: _installcheck_world
 	    LOCAL_MTREE=${LOCAL_MTREE:Q} distrib-dirs
 .endif
 	${_+_}cd ${.CURDIR}; ${IMAKE} re${.TARGET:S/world$//}; \
-	    ${IMAKEENV} rm -rf ${INSTALLTMP}
+	    ${IMAKEENV} rm -rf ${INSTALLTMPDIR}
 .if make(distributeworld)
 .for dist in ${EXTRA_DISTRIBUTIONS}
 	find ${DESTDIR}/${DISTDIR}/${dist} -mindepth 1 -empty -delete