diff --git a/Makefile b/Makefile
index 9a99895..6402ab5 100644
--- a/Makefile
+++ b/Makefile
@@ -13,11 +13,11 @@ GITVERSION:=$(shell git rev-parse HEAD)
 
 ARCH:=$(shell dpkg-architecture -qDEB_BUILD_ARCH)
 
-GEN_DEB=${GEN_PACKAGE}_${DEB_VERSION_UPSTREAM_REVISION}_${ARCH}.deb
-DOC_DEB=${DOC_PACKAGE}_${DEB_VERSION_UPSTREAM_REVISION}_all.deb
+GEN_DEB=$(GEN_PACKAGE)_$(DEB_VERSION_UPSTREAM_REVISION)_$(ARCH).deb
+DOC_DEB=$(DOC_PACKAGE)_$(DEB_VERSION_UPSTREAM_REVISION)_all.deb
 
 export SOURCE_DATE_EPOCH ?= $(shell dpkg-parsechangelog -STimestamp)
-SOURCE_DATE_HUMAN := $(shell date -d "@${SOURCE_DATE_EPOCH}")
+SOURCE_DATE_HUMAN := $(shell date -d "@$(SOURCE_DATE_EPOCH)")
 
 
 all: index.html
@@ -27,21 +27,21 @@ verify-images: png-verify.pl
 	for i in ./images/screenshot/*.png; do ./png-verify.pl $$i; done
 
 ADOC_SOURCES_GUESS=$(filter-out %-synopsis.adoc %-opts.adoc %-table.adoc, $(wildcard *.adoc))
-.pmg-doc-depends link-refs.json: ${ADOC_SOURCES_GUESS} scan-adoc-refs
+.pmg-doc-depends link-refs.json: $(ADOC_SOURCES_GUESS) scan-adoc-refs
 	./scan-adoc-refs *.adoc --depends .pmg-doc-depends.tmp > link-refs.json.tmp
 	@cmp --quiet .pmg-doc-depends .pmg-doc-depends.tmp || mv .pmg-doc-depends.tmp .pmg-doc-depends
 	@cmp --quiet link-refs.json link-refs.json.tmp || mv link-refs.json.tmp link-refs.json
 
 pmg-doc-generator.mk: .pmg-doc-depends pmg-doc-generator.mk.in
 	cat pmg-doc-generator.mk.in .pmg-doc-depends > $@.tmp
-	sed -i "s/@RELEASE@$$/${DEB_VERSION_UPSTREAM}/" $@.tmp
+	sed -i "s/@RELEASE@$$/$(DEB_VERSION_UPSTREAM)/" $@.tmp
 	mv $@.tmp $@
 
 -include ./pmg-doc-generator.mk
 
 GEN_DEB_SOURCES=				\
 	pmg-doc-generator.mk			\
-	${MANUAL_SOURCES}			\
+	$(MANUAL_SOURCES)			\
 	docinfo.xml
 
 GEN_SCRIPTS=					\
@@ -62,7 +62,7 @@ API_VIEWER_SOURCES=				\
 
 asciidoc-pmg: asciidoc-pmg.in link-refs.json
 	cat asciidoc-pmg.in link-refs.json >asciidoc-pmg.tmp
-	sed -e s/@RELEASE@/${DOCRELEASE}/ -i asciidoc-pmg.tmp
+	sed -e s/@RELEASE@/$(DOCRELEASE)/ -i asciidoc-pmg.tmp
 	chmod +x asciidoc-pmg.tmp
 	mv asciidoc-pmg.tmp asciidoc-pmg
 
@@ -73,15 +73,15 @@ INDEX_INCLUDES=								\
 	man1-index-table.adoc						\
 	man5-index-table.adoc						\
 	man8-index-table.adoc						\
-	$(sort $(addsuffix .html, ${MANUAL_PAGES}) ${CHAPTER_LIST})
+	$(sort $(addsuffix .html, $(MANUAL_PAGES)) $(CHAPTER_LIST))
 
-ADOC_STDARG=-b $(shell pwd)/asciidoc/pmg-html -f asciidoc/asciidoc-pmg.conf -a icons -a data-uri -a "date=${SOURCE_DATE_HUMAN}" -a "revnumber=${DOCRELEASE}"
+ADOC_STDARG=-b $(shell pwd)/asciidoc/pmg-html -f asciidoc/asciidoc-pmg.conf -a icons -a data-uri -a "date=$(SOURCE_DATE_HUMAN)" -a "revnumber=$(DOCRELEASE)"
 
 BROWSER?=xdg-open
 
 
 README.html: README.adoc
-	asciidoc -a toc ${ADOC_STDARG} -o $@ $<
+	asciidoc -a toc $(ADOC_STDARG) -o $@ $<
 
 .PHONY: index
 index: index.html
@@ -103,13 +103,13 @@ man8-index-table.adoc: asciidoc-pmg
 	./asciidoc-pmg man8page-table >$@.tmp
 	mv $@.tmp $@
 
-index.html: index.adoc ${API_VIEWER_SOURCES} ${INDEX_INCLUDES}
-	asciidoc ${ADOC_STDARG} -o $@ index.adoc
+index.html: index.adoc $(API_VIEWER_SOURCES) $(INDEX_INCLUDES)
+	asciidoc $(ADOC_STDARG) -o $@ index.adoc
 
-pmg-admin-guide.html: ${PMG_ADMIN_GUIDE_ADOCDEPENDS}
-	asciidoc -a pmglogo ${ADOC_STDARG} -o $@ pmg-admin-guide.adoc
+pmg-admin-guide.html: $(PMG_ADMIN_GUIDE_ADOCDEPENDS)
+	asciidoc -a pmglogo $(ADOC_STDARG) -o $@ pmg-admin-guide.adoc
 
-pmg-admin-guide.chunked: ${PMG_ADMIN_GUIDE_ADOCDEPENDS}
+pmg-admin-guide.chunked: $(PMG_ADMIN_GUIDE_ADOCDEPENDS)
 	rm -rf $@.tmp $@
 	mkdir $@.tmp
 	a2x -D $@.tmp -a docinfo -a docinfo1 -a icons -f chunked pmg-admin-guide.adoc
@@ -121,45 +121,45 @@ PMG_DBLATEX_OPTS='-p ./asciidoc/pmg-dblatex.xsl -s asciidoc/dblatex-custom.sty -
 YEAR:=$(shell date "+%Y")
 
 pmg-admin-guide-docinfo.xml: pmg-admin-guide-docinfo.xml.in
-	sed -e 's/@RELEASE@/${DOCRELEASE}/' -e 's/@YEAR@/${YEAR}/' <$< >$@
+	sed -e 's/@RELEASE@/$(DOCRELEASE)/' -e 's/@YEAR@/$(YEAR)/' <$< >$@
 
 pmg-copyright.adoc: pmg-copyright.adoc.in
-	sed -e 's/@YEAR@/${YEAR}/' <$< >$@
+	sed -e 's/@YEAR@/$(YEAR)/' <$< >$@
 
-pmg-admin-guide.pdf: ${PMG_ADMIN_GUIDE_ADOCDEPENDS} docinfo.xml pmg-admin-guide-docinfo.xml
+pmg-admin-guide.pdf: $(PMG_ADMIN_GUIDE_ADOCDEPENDS) docinfo.xml pmg-admin-guide-docinfo.xml
 	rsvg-convert -f pdf -o proxmox-logo.pdf images/proxmox-logo.svg
 	rsvg-convert -f pdf -o proxmox-ci-header.pdf images/proxmox-ci-header.svg
-	grep ">Release ${DOCRELEASE}<" pmg-admin-guide-docinfo.xml || (echo "wrong release in  pmg-admin-guide-docinfo.xml" && false);
-	a2x -a docinfo -a docinfo1 -f pdf -L --asciidoc-opts="${PMG_DOCBOOK_CONF}" --dblatex-opts ${PMG_DBLATEX_OPTS} pmg-admin-guide.adoc
+	grep ">Release $(DOCRELEASE)<" pmg-admin-guide-docinfo.xml || (echo "wrong release in  pmg-admin-guide-docinfo.xml" && false);
+	a2x -a docinfo -a docinfo1 -f pdf -L --asciidoc-opts="$(PMG_DOCBOOK_CONF)" --dblatex-opts $(PMG_DBLATEX_OPTS) pmg-admin-guide.adoc
 	rm proxmox-logo.pdf proxmox-ci-header.pdf
 
-pmg-admin-guide.epub: ${PMG_ADMIN_GUIDE_ADOCDEPENDS}
+pmg-admin-guide.epub: $(PMG_ADMIN_GUIDE_ADOCDEPENDS)
 	rm -rf $@.tmp $@
 	mkdir $@.tmp
-	a2x -D $@.tmp -f epub --asciidoc-opts="${PMG_DOCBOOK_CONF}" pmg-admin-guide.adoc
+	a2x -D $@.tmp -f epub --asciidoc-opts="$(PMG_DOCBOOK_CONF)" pmg-admin-guide.adoc
 	mv $@.tmp/$@ $@
 
 api-viewer/apidata.js: extractapi.pl
 	./extractapi.pl >$@
 
-api-viewer/apidoc.js: ${API_VIEWER_FILES}
-	cat ${API_VIEWER_FILES} >$@.tmp
+api-viewer/apidoc.js: $(API_VIEWER_FILES)
+	cat $(API_VIEWER_FILES) >$@.tmp
 	mv $@.tmp $@
 
 .PHONY: dinstall
-dinstall: ${GEN_DEB} ${DOC_DEB}
-	dpkg -i ${GEN_DEB} ${DOC_DEB}
+dinstall: $(GEN_DEB) $(DOC_DEB)
+	dpkg -i $(GEN_DEB) $(DOC_DEB)
 
 .PHONY: deb
-deb: ${DOC_DEB}
+deb: $(DOC_DEB)
 
-${GEN_DEB}: ${DOC_DEB}
+$(GEN_DEB): $(DOC_DEB)
 
-${DOC_DEB}:
-	rm -f ${GEN_DEB} ${DOC_DEB}
+$(DOC_DEB):
+	rm -f $(GEN_DEB) $(DOC_DEB)
 	rm -rf build
 	rsync -a * build/
-	echo "git clone git://git.proxmox.com/git/pmg-docs.git\\ngit checkout ${GITVERSION}" > build/debian/SOURCE
+	echo "git clone git://git.proxmox.com/git/pmg-docs.git\\ngit checkout $(GITVERSION)" > build/debian/SOURCE
 	cd build; dpkg-buildpackage -b -us -uc
 	lintian $(DOC_DEB) $(GEN_DEB)
 
@@ -172,33 +172,33 @@ install: gen-install doc-install
 
 .PHONY: gen-install
 gen-install: $(GEN_DEB_SOURCES) asciidoc-pmg
-	install -dm755 ${DESTDIR}/usr/bin
-	install -dm755 $(DESTDIR)/usr/share/${GEN_PACKAGE}
+	install -dm755 $(DESTDIR)/usr/bin
+	install -dm755 $(DESTDIR)/usr/share/$(GEN_PACKAGE)
 	# install files
-	install -m 0644 ${GEN_DEB_SOURCES} $(DESTDIR)/usr/share/${GEN_PACKAGE}
-	install -m 0755 ${GEN_SCRIPTS} $(DESTDIR)/usr/share/${GEN_PACKAGE}
+	install -m 0644 $(GEN_DEB_SOURCES) $(DESTDIR)/usr/share/$(GEN_PACKAGE)
+	install -m 0755 $(GEN_SCRIPTS) $(DESTDIR)/usr/share/$(GEN_PACKAGE)
 	# install asciidoc-pmg
 	install -m 0755 asciidoc-pmg $(DESTDIR)/usr/bin/
-	install -dm755 $(DESTDIR)/usr/share/${GEN_PACKAGE}/asciidoc/
-	install -m 0644 asciidoc/asciidoc-pmg.conf $(DESTDIR)/usr/share/${GEN_PACKAGE}/asciidoc/
-	install -m 0644 asciidoc/pmg-html.conf $(DESTDIR)/usr/share/${GEN_PACKAGE}/asciidoc/
+	install -dm755 $(DESTDIR)/usr/share/$(GEN_PACKAGE)/asciidoc/
+	install -m 0644 asciidoc/asciidoc-pmg.conf $(DESTDIR)/usr/share/$(GEN_PACKAGE)/asciidoc/
+	install -m 0644 asciidoc/pmg-html.conf $(DESTDIR)/usr/share/$(GEN_PACKAGE)/asciidoc/
 
 .PHONY: doc-install
 doc-install: index.html $(API_VIEWER_SOURCES) verify-images
 	# install files for pmgdocs package
-	install -dm755 $(DESTDIR)/usr/share/${DOC_PACKAGE}
-	install -dm755 $(DESTDIR)/usr/share/doc/${DOC_PACKAGE}
-	install -m 0644 index.html ${INDEX_INCLUDES} $(DESTDIR)/usr/share/${DOC_PACKAGE}
+	install -dm755 $(DESTDIR)/usr/share/$(DOC_PACKAGE)
+	install -dm755 $(DESTDIR)/usr/share/doc/$(DOC_PACKAGE)
+	install -m 0644 index.html $(INDEX_INCLUDES) $(DESTDIR)/usr/share/$(DOC_PACKAGE)
 	# install screenshot images
-	install -dm755 $(DESTDIR)/usr/share/${DOC_PACKAGE}/images/screenshot
-	install -m 0644 images/screenshot/*.png $(DESTDIR)/usr/share/${DOC_PACKAGE}/images/screenshot
+	install -dm755 $(DESTDIR)/usr/share/$(DOC_PACKAGE)/images/screenshot
+	install -m 0644 images/screenshot/*.png $(DESTDIR)/usr/share/$(DOC_PACKAGE)/images/screenshot
 	# install api doc viewer
-	install -dm755 $(DESTDIR)/usr/share/${DOC_PACKAGE}/api-viewer
-	install -m 0644 ${API_VIEWER_SOURCES} $(DESTDIR)/usr/share/${DOC_PACKAGE}/api-viewer
+	install -dm755 $(DESTDIR)/usr/share/$(DOC_PACKAGE)/api-viewer
+	install -m 0644 $(API_VIEWER_SOURCES) $(DESTDIR)/usr/share/$(DOC_PACKAGE)/api-viewer
 
 .PHONY: upload
-upload: ${GEN_DEB} ${DOC_DEB}
-	tar cf - ${GEN_DEB} ${DOC_DEB} | ssh -X repoman@repo.proxmox.com -- upload --product pmg --dist bullseye
+upload: $(GEN_DEB) $(DOC_DEB)
+	tar cf - $(GEN_DEB) $(DOC_DEB) | ssh -X repoman@repo.proxmox.com -- upload --product pmg --dist bullseye
 
 .PHONY: update
 update: clean