diff --git a/include/git.sh b/include/git.sh
index 1c458f08..413af4cc 100755
--- a/include/git.sh
+++ b/include/git.sh
@@ -15,8 +15,7 @@ fetch_project_trees()
 	[ -z "${rev}" ] && err "fetch_project_trees $target: undefined rev"
 	[ -d "src/${project}/${tree}" ] && \
 		printf "download/%s %s (%s): exists\n" \
-		    "${project}" "${tree}" "${_target}" 1>&2 && \
-		return 1
+		    "${project}" "${tree}" "${_target}" 1>&2 && return 0
 	prepare_new_tree
 }
 
@@ -30,7 +29,7 @@ fetch_from_upstream()
 
 fetch_config()
 {
-	x_ rm -f "${cfgsdir}/"*/seen
+	rm -f "${cfgsdir}/"*/seen || err "fetch_config ${cfgsdir}: !rm seen"
 	while true; do
 		eval "$(setvars "" rev tree)"
 		_xm="fetch_config ${project}/${_target}"
@@ -50,7 +49,7 @@ load_target_config()
 	. "${cfgsdir}/${1}/target.cfg" || \
 	    err "load_target_config ${cfgsdir}/${1}: cannot load config"
 
-	x_ touch "${cfgsdir}/${1}/seen"
+	touch "${cfgsdir}/${1}/seen" || err "load_config $cfgsdir/$1: !mk seen"
 }
 
 prepare_new_tree()
@@ -74,7 +73,7 @@ fetch_project_repo()
 	verify_config
 
 	clone_project
-	[ "${depend}" = "" ] || for d in ${depend} ; do
+	[ -z "${depend}" ] || for d in ${depend} ; do
 		x_ ./update trees -f ${d}
 	done
 	x_ rm -Rf "${tmp_git_dir}"
diff --git a/script/update/release b/script/update/release
index c60f36e5..6188d793 100755
--- a/script/update/release
+++ b/script/update/release
@@ -46,7 +46,7 @@ mkvdir()
 	git clone . "${srcdir}" || err "mkdir: !gitclone \"${srcdir}\""
 	[ -z "${_nogit}" ] || x_ rm -Rf ".git"
 
-	rm -Rf "${srcdir}/.git"
+	rm -Rf "${srcdir}/.git" || err "mkvdir: !rm -Rf ${srcdir}/.git"
 	insert_version_files "${srcdir}" || err "mkvdir ${srcdir}: versionfile"
 }
 
@@ -201,6 +201,8 @@ insert_copying_files()
 	x_ cp "src/seabios/default/COPYING" "${l}/COPYING.coreboot"
 	x_ cp "src/seabios/default/COPYING.LESSER" "${l}/COPYING.LESSER.seabios"
 	x_ cp -R "src/u-boot/default/Licenses" "${l}/COPYING.u-boot"
+	x_ printf "Multiple licenses. Check corresponding %s source archive\n" \
+	    "${projectname}" > "${1}/COPYING"
 }
 
 mkrom_tarball()
diff --git a/script/update/trees b/script/update/trees
index 926159cf..119586a5 100755
--- a/script/update/trees
+++ b/script/update/trees
@@ -16,8 +16,6 @@ export LOCALVERSION="-${projectname}-${version%%-*}"
 eval "$(setvars "" arch cfgsdir codedir config config_name crossgcc_ada mode \
     elfdir listfile project romtype target target_dir targets tree _f target1)"
 
-tmpclean="$(mktemp -d -t makeclean.XXXXXXXXXX)"
-
 main()
 {
 	while getopts f:b:m:u:c:x:s:l:n: option
@@ -37,7 +35,7 @@ main()
 		esac
 		shift; project="${OPTARG#src/}"; shift
 	done
-	[ -z "${_f}" ] && err "flag not specified (-m, -u, -b, -c, -x, -f, -s, -l or -n)"
+	[ -z "${_f}" ] && err "missing flag (-m/-u/-b/-c/-x/-f/-s/-l/-n)"
 	[ -z "${project}" ] && err "project name not specified"
 
 	if [ ! -f "config/${project}/build.list" ]; then
@@ -51,10 +49,7 @@ build_projects()
 {
 	[ $# -gt 0 ] && x_ ./update trees ${_f} ${@}
 
-	if [ "${mode}" = "fetch" ]; then
-		fetch_project_repo
-		return 0
-	fi
+	[ "${mode}" = "fetch" ] && fetch_project_repo && return 0
 
 	codedir="src/${project}"
 	[ -d "${codedir}" ] || x_ ./update trees -f "${project}"
@@ -140,10 +135,7 @@ handle_src_tree()
 	romtype="normal"
 	target_dir="${cfgsdir}/${target}"
 
-	if [ "${mode}" = "fetch" ]; then
-		fetch_project_trees
-		return 1
-	fi
+	[ "${mode}" = "fetch" ] && fetch_project_trees && return 1
 
 	x_ mkdir -p "${elfdir}/${target}"
 	eval "$(setvars "" arch tree)"
@@ -151,10 +143,9 @@ handle_src_tree()
 	. "${target_dir}/target.cfg" || \
 	    err "handle_src_tree ${target_dir}: cannot load target.cfg"
 
-	[ -z "${tree}" ] && \
-		err "handle_src_tree: ${target_dir}: tree undefined"
-	[ -z "${arch}" ] && \
-		err "handle_src_tree: ${target_dir}: undefined cpu type"
+	for ix in arch tree; do
+		eval "[ -z \"\${$ix}\" ] && err \"handle_src: $ix undefined\""
+	done
 
 	codedir="src/${project}/${tree}"
 
@@ -166,21 +157,14 @@ handle_src_tree()
 			return 1
 		fi
 		x_ ./update trees -f "${project}" "${target}"
-	elif [ "${mode}" = "distclean" ] || \
-	    [ "${mode}" = "crossgcc-clean" ]; then
-		[ -f "${tmpclean}/${tree}" ] && return 1
-		touch "${tmpclean}/${tree}"
 	fi
 
 	[ "${target1}" = "utils" ] && [ "${project}" = "coreboot" ] && return 0
 	[ "$project" != "coreboot" ] && [ "$project" != "u-boot" ] && return 0
 
 	# u-boot and coreboot are both compiled with coreboot's crossgcc
-	[ ! -z ${mode} ] || check_cross_compiler || \
-	    err "handle_src_tree ${project}/${target}: crossgcc"
-	cbfstool="cbutils/${tree}/cbfstool"
-	[ -f "${cbfstool}" ] && return 0
-	x_ ./update trees -b coreboot utils "${tree}"
+	[ -z ${mode} ] || return 0
+	check_cross_compiler
 }
 
 # set up cross-compiler (coreboot crossgcc) for u-boot and coreboot
@@ -189,42 +173,35 @@ check_cross_compiler()
 {
 	[ "${crossgcc_ada}" = "y" ] || [ "${crossgcc_ada}" = "n" ] || \
 		crossgcc_ada="y"
-	[ "${crossgcc_ada}" != "y" ] && \
-		export BUILD_LANGUAGES=c
+	[ "${crossgcc_ada}" = "y" ] || export BUILD_LANGUAGES=c
 
 	cbdir="src/coreboot/${tree}"
-	[ "${project}" != "coreboot" ] && \
-		cbdir="src/coreboot/default"
+	[ "${project}" != "coreboot" ] && cbdir="src/coreboot/default"
 
 	# only true if not building coreboot:
 	ctarget="${cbdir#src/coreboot/}"
-	[ -d "${cbdir}" ] || \
-		x_ ./update trees -f coreboot ${ctarget}
+	[ -d "${cbdir}" ] || x_ ./update trees -f coreboot ${ctarget}
 
 	if [ "${arch}" = "x86_32" ] || [ "${arch}" = "x86_64" ]; then
 		[ -d "${cbdir}/util/crossgcc/xgcc/i386-elf/" ] || \
-			make -C "${cbdir}" crossgcc-i386 CPUS=$(nproc) || \
-			    return 1
+			x_ make -C "${cbdir}" crossgcc-i386 CPUS=$(nproc)
 		case "$(uname -m)" in
 			x86*|i*86|amd64) : ;;
 			*) export CROSS_COMPILE=i386-elf- ;;
 		esac
 	elif [ "${arch}" = "ARMv7" ]; then
 		[ -d "${cbdir}/util/crossgcc/xgcc/arm-eabi/" ] || \
-			make -C "${cbdir}" crossgcc-arm CPUS=$(nproc) || \
-			    return 1
+			x_ make -C "${cbdir}" crossgcc-arm CPUS=$(nproc)
 		case "$(uname -m)" in
 			arm|arm32|armv6*|armv7*) : ;;
 			*) export CROSS_COMPILE=arm-eabi- ;;
 		esac
 	elif [ "${arch}" = "AArch64" ]; then
 		[ -d "${cbdir}/util/crossgcc/xgcc/aarch64-elf/" ] || \
-			make -C "${cbdir}" crossgcc-aarch64 CPUS=$(nproc) || \
-			    return 1
+			x_ make -C "${cbdir}" crossgcc-aarch64 CPUS=$(nproc)
 		# aarch64 also needs armv7 toolchain for arm-trusted-firmware
 		[ -d "${cbdir}/util/crossgcc/xgcc/arm-eabi/" ] || \
-			make -C "${cbdir}" crossgcc-arm CPUS=$(nproc) || \
-			    return 1
+			x_ make -C "${cbdir}" crossgcc-arm CPUS=$(nproc)
 		case "$(uname -m)" in
 			arm64|aarch64) : ;;
 			*) export CROSS_COMPILE=aarch64-elf- ;;