diff --git a/Makefile.inc1 b/Makefile.inc1
index 9bb522f088ff..37b80e5d96dc 100644
--- a/Makefile.inc1
+++ b/Makefile.inc1
@@ -126,11 +126,15 @@ MAKEOBJDIRPREFIX?=	/usr/obj
 TARGET_ARCH?=	${MACHINE_ARCH}
 .if ${TARGET_ARCH} == ${MACHINE_ARCH}
 TARGET?=	${MACHINE}
-TARGET_CPUTYPE?=	${CPUTYPE}
+TARGET_CPUTYPE?=${CPUTYPE}
 .else
 TARGET?=	${TARGET_ARCH}
 TARGET_CPUTYPE?=
 .endif
+_CPUTYPE!=	cd ${.CURDIR}; ${MAKE} CPUTYPE=${TARGET_CPUTYPE} -V CPUTYPE
+.if ${_CPUTYPE} != ${TARGET_CPUTYPE}
+.error CPUTYPE global should be set with ?=.
+.endif
 .if make(buildworld)
 BUILD_ARCH!=	sysctl -n hw.machine_arch
 .if ${MACHINE_ARCH} != ${BUILD_ARCH}
@@ -175,6 +179,7 @@ INSTALLTMP!=	/usr/bin/mktemp -d -u -t install
 CROSSENV=	MAKEOBJDIRPREFIX=${OBJTREE} \
 		MACHINE_ARCH=${TARGET_ARCH} \
 		MACHINE=${TARGET} \
+		CPUTYPE=${TARGET_CPUTYPE} \
 		OBJFORMAT_PATH=${WORLDTMP}/usr/libexec \
 		GROFF_BIN_PATH=${WORLDTMP}/usr/bin \
 		GROFF_FONT_PATH=${WORLDTMP}/usr/share/groff_font \
@@ -476,7 +481,7 @@ buildkernel:
 .endif
 	cd ${KRNLOBJDIR}/${_kernel}; \
 	    MAKESRCPATH=${KRNLSRCDIR}/dev/aic7xxx/aicasm \
-	    ${MAKE} -DBOOTSTRAPPING -f ${KRNLSRCDIR}/dev/aic7xxx/aicasm/Makefile
+	    ${MAKE} -DNO_CPU_CFLAGS -f ${KRNLSRCDIR}/dev/aic7xxx/aicasm/Makefile
 .if !defined(NO_KERNELDEPEND)
 	cd ${KRNLOBJDIR}/${_kernel}; \
 	    ${KMAKEENV} ${MAKE} KERNEL=${INSTKERNNAME} depend
diff --git a/share/examples/etc/make.conf b/share/examples/etc/make.conf
index 0c3f1d4f76f5..023a45f9f489 100644
--- a/share/examples/etc/make.conf
+++ b/share/examples/etc/make.conf
@@ -29,7 +29,9 @@
 #   Alpha/AXP architecture: ev6 pca56 ev56 ev5 ev45 ev4
 #   Intel ia64 architecture: itanium
 #
-#CPUTYPE=i686
+# (?= allows to buildworld for a different CPUTYPE.)
+#
+#CPUTYPE?=i686
 #NO_CPU_CFLAGS=	true	# Don't add -march=<cpu> to CFLAGS automatically
 #NO_CPU_COPTFLAGS=true	# Don't add -march=<cpu> to COPTFLAGS automatically
 #
diff --git a/share/mk/bsd.cpu.mk b/share/mk/bsd.cpu.mk
index 7a9d7e241e8f..1fd7427af6a2 100644
--- a/share/mk/bsd.cpu.mk
+++ b/share/mk/bsd.cpu.mk
@@ -1,16 +1,10 @@
 # $FreeBSD$
 
-# Allow TARGET_CPUTYPE to override CPUTYPE to handle the cross-build case.
-
-.if defined(TARGET_CPUTYPE)
-CPUTYPE = ${TARGET_CPUTYPE}
-.endif
-
 # Set default CPU compile flags and baseline CPUTYPE for each arch.  The
 # compile flags must support the minimum CPU type for each architecture but
 # may tune support for more advanced processors.
 
-.if !defined(CPUTYPE) || ${CPUTYPE} == ""
+.if !defined(CPUTYPE) || empty(CPUTYPE)
 . if ${MACHINE_ARCH} == "i386"
 _CPUCFLAGS = -mcpu=pentiumpro
 CPUTYPE = i386