diff --git a/arch/ppc/boot/Makefile b/arch/ppc/boot/Makefile
index 487dc66dcc74..500497e3c72d 100644
--- a/arch/ppc/boot/Makefile
+++ b/arch/ppc/boot/Makefile
@@ -13,6 +13,8 @@
 # modified by Cort (cort@cs.nmt.edu)
 #
 
+# KBUILD_CFLAGS used when building rest of boot (takes effect recursively)
+KBUILD_CFLAGS 	+= -fno-builtin -D__BOOTER__ -Iarch/$(ARCH)/boot/include
 HOSTCFLAGS	+= -Iarch/$(ARCH)/boot/include
 
 BOOT_TARGETS	= zImage zImage.initrd znetboot znetboot.initrd
diff --git a/arch/xtensa/boot/Makefile b/arch/xtensa/boot/Makefile
index 9c5185f605b6..40aa55b485be 100644
--- a/arch/xtensa/boot/Makefile
+++ b/arch/xtensa/boot/Makefile
@@ -8,7 +8,8 @@
 #
 
 
-EXTRA_CFLAGS	+= -fno-builtin -Iarch/$(ARCH)/boot/include
+# KBUILD_CFLAGS used when building rest of boot (takes effect recursively)
+KBUILD_CFLAGS	+= -fno-builtin -Iarch/$(ARCH)/boot/include
 HOSTFLAGS	+= -Iarch/$(ARCH)/boot/include
 
 BIG_ENDIAN	:= $(shell echo -e __XTENSA_EB__ | $(CC) -E - | grep -v "\#")