--- a/Makefile
+++ b/Makefile
@@ -5,7 +5,7 @@
 ifeq ($(KERNELRELEASE),)
 
 MAKEFLAGS += --no-print-directory
-SHELL := /bin/bash
+SHELL := /usr/bin/env bash
 BACKPORT_DIR := $(shell pwd)
 
 KMODDIR ?= updates
@@ -19,6 +19,7 @@ KLIB_BUILD ?= $(KLIB)/build/
 KERNEL_CONFIG := $(KLIB_BUILD)/.config
 KERNEL_MAKEFILE := $(KLIB_BUILD)/Makefile
 CONFIG_MD5 := $(shell md5sum $(KERNEL_CONFIG) 2>/dev/null | sed 's/\s.*//')
+STAMP_KERNEL_CONFIG := .kernel_config_md5_$(CONFIG_MD5)
 
 export KLIB KLIB_BUILD BACKPORT_DIR KMODDIR KMODPATH_ARG
 
@@ -36,7 +37,8 @@ mrproper:
 	@rm -f .kernel_config_md5 Kconfig.versions Kconfig.kernel
 	@rm -f backport-include/backport/autoconf.h
 
-.DEFAULT:
+.SILENT: $(STAMP_KERNEL_CONFIG)
+$(STAMP_KERNEL_CONFIG):
 	@set -e ; test -f local-symbols || (						\
 	echo "/--------------"								;\
 	echo "| You shouldn't run make in the backports tree, but only in"		;\
@@ -60,57 +62,62 @@ mrproper:
 	echo "| (that isn't currently running.)"					;\
 	echo "\\--"									;\
 	false)
-	@set -e ; if [ "$$(cat .kernel_config_md5 2>/dev/null)" != "$(CONFIG_MD5)" ]	;\
-	then 										\
-		echo -n "Generating local configuration database from kernel ..."	;\
-		grep -v -f local-symbols $(KERNEL_CONFIG) | grep = | (			\
-			while read l ; do						\
-				if [ "$${l:0:7}" != "CONFIG_" ] ; then			\
-					continue					;\
-				fi							;\
-				l=$${l:7}						;\
-				n=$${l%%=*}						;\
-				v=$${l#*=}						;\
-				if [ "$$v" = "m" ] ; then				\
-					echo config $$n					;\
-					echo '    tristate' 				;\
-				elif [ "$$v" = "y" ] ; then				\
-					echo config $$n					;\
-					echo '    bool'					;\
-				else							\
-					continue					;\
-				fi							;\
-				echo "    default $$v"					;\
-				echo ""							;\
-			done								\
-		) > Kconfig.kernel							;\
-		kver=$$($(MAKE) --no-print-directory -C $(KLIB_BUILD) M=$(BACKPORT_DIR)	\
-			kernelversion |	sed 's/^\(\([3-6]\|2\.6\)\.[0-9]\+\).*/\1/;t;d');\
-		test "$$kver" != "" || echo "Kernel version parse failed!"		;\
-		test "$$kver" != ""							;\
-		kvers="$$kvers $$(seq 0 20 | sed 's/^/4./')"				;\
-		kvers="$$kvers $$(seq 0 19 | sed 's/^/5./')"				;\
-		kvers="$$kvers $$(seq 0 20 | sed 's/^/6./')"				;\
-		print=0									;\
-		for v in $$kvers ; do							\
-			if [ "$$print" = "1" ] ; then					\
-				echo config KERNEL_$$(echo $$v | tr . _)	;\
-				echo "    def_bool y"					;\
-			fi								;\
-			if [ "$$v" = "$$kver" ] ; then print=1 ; fi			;\
-		done > Kconfig.versions							;\
-		# RHEL as well, sadly we need to grep for it				;\
-		RHEL_MAJOR=$$(grep '^RHEL_MAJOR' $(KERNEL_MAKEFILE) | 			\
-					sed 's/.*=\s*\([0-9]*\)/\1/;t;d')		;\
-		RHEL_MINOR=$$(grep '^RHEL_MINOR' $(KERNEL_MAKEFILE) | 			\
-					sed 's/.*=\s*\([0-9]*\)/\1/;t;d')		;\
-		for v in $$(seq 0 $$RHEL_MINOR) ; do 					\
-			echo config BACKPORT_RHEL_KERNEL_$${RHEL_MAJOR}_$$v		;\
-			echo "    def_bool y"						;\
-		done >> Kconfig.versions						;\
-		echo " done."								;\
-	fi										;\
-	echo "$(CONFIG_MD5)" > .kernel_config_md5
+	@rm -f .kernel_config_md5_*
+	@touch $@
+
+Kconfig.kernel: $(STAMP_KERNEL_CONFIG) local-symbols
+	@printf "Generating local configuration database from kernel ..."
+	@grep -v -f local-symbols $(KERNEL_CONFIG) | grep = | (			\
+		while read l ; do						\
+			if [ "$${l:0:7}" != "CONFIG_" ] ; then			\
+				continue					;\
+			fi							;\
+			l=$${l:7}						;\
+			n=$${l%%=*}						;\
+			v=$${l#*=}						;\
+			if [ "$$v" = "m" ] ; then				\
+				echo config $$n					;\
+				echo '    tristate' 				;\
+			elif [ "$$v" = "y" ] ; then				\
+				echo config $$n					;\
+				echo '    bool'					;\
+			else							\
+				continue					;\
+			fi							;\
+			echo "    default $$v"					;\
+			echo ""							;\
+		done								\
+	) > $@
+	@echo " done."
+
+Kconfig.versions: Kconfig.kernel
+	@kver=$$($(MAKE) --no-print-directory -C $(KLIB_BUILD) M=$(BACKPORT_DIR)	\
+		kernelversion |	sed 's/^\(\([3-6]\|2\.6\)\.[0-9]\+\).*/\1/;t;d');\
+	test "$$kver" != "" || echo "Kernel version parse failed!"		;\
+	test "$$kver" != ""							;\
+	kvers="$$kvers $$(seq 0 20 | sed 's/^/4./')"				;\
+	kvers="$$kvers $$(seq 0 19 | sed 's/^/5./')"				;\
+	kvers="$$kvers $$(seq 0 20 | sed 's/^/6./')"				;\
+	print=0									;\
+	for v in $$kvers ; do							\
+		if [ "$$print" = "1" ] ; then					\
+			echo config KERNEL_$$(echo $$v | tr . _)	;\
+			echo "    def_bool y"					;\
+		fi								;\
+		if [ "$$v" = "$$kver" ] ; then print=1 ; fi			;\
+	done > Kconfig.versions							;\
+	# RHEL as well, sadly we need to grep for it				;\
+	RHEL_MAJOR=$$(grep '^RHEL_MAJOR' $(KERNEL_MAKEFILE) | 			\
+				sed 's/.*=\s*\([0-9]*\)/\1/;t;d')		;\
+	RHEL_MINOR=$$(grep '^RHEL_MINOR' $(KERNEL_MAKEFILE) | 			\
+				sed 's/.*=\s*\([0-9]*\)/\1/;t;d')		;\
+	for v in $$(seq 0 $$RHEL_MINOR) ; do 					\
+		echo config BACKPORT_RHEL_KERNEL_$${RHEL_MAJOR}_$$v		;\
+		echo "    def_bool y"						;\
+	done >> $@
+
+.DEFAULT:
+	@$(MAKE) Kconfig.versions
 	@$(MAKE) -f Makefile.real "$@"
 
 .PHONY: defconfig-help
--- a/Makefile.real
+++ b/Makefile.real
@@ -59,7 +59,7 @@ defconfig-%::
 
 backport-include/backport/autoconf.h: .config Kconfig.versions Kconfig.kernel
 	@$(MAKE) oldconfig
-	@echo -n "Building backport-include/backport/autoconf.h ..."
+	@printf "Building backport-include/backport/autoconf.h ..."
 	@grep -f local-symbols .config | (				\
 		echo "#ifndef COMPAT_AUTOCONF_INCLUDED"			;\
 		echo "#define COMPAT_AUTOCONF_INCLUDED"			;\
@@ -80,7 +80,12 @@ backport-include/backport/autoconf.h: .c
 			esac						;\
 		done							;\
 		echo "#endif /* COMPAT_AUTOCONF_INCLUDED */"		;\
-	) > backport-include/backport/autoconf.h
+	) > $@.new
+	@if cmp -s $@ $@.new; then \
+		rm -f $@.new; \
+	else \
+		mv $@.new $@; \
+	fi
 	@echo " done."
 
 .PHONY: modules