diff --git a/Makefile b/Makefile
index bced101..0bf1794 100644
--- a/Makefile
+++ b/Makefile
@@ -3,7 +3,8 @@ VERSION	= 0.0.0
 SUBDIRS	= doc
 RM	= rm -f
 LN	= ln -f
-TAR	= tar -czvf
+TAR	= tar
+MKDIR	= mkdir -m 0755 -p
 
 
 all: subdirs
@@ -20,7 +21,7 @@ distclean:
 dist:
 	$(RM) -r -- $(PACKAGE)-$(VERSION)
 	$(LN) -s -- . $(PACKAGE)-$(VERSION)
-	@$(TAR) $(PACKAGE)-$(VERSION).tar.gz -- \
+	@$(TAR) -czvf $(PACKAGE)-$(VERSION).tar.gz -- \
 		$(PACKAGE)-$(VERSION)/doc/Makefile \
 		$(PACKAGE)-$(VERSION)/doc/docbook.sh \
 		$(PACKAGE)-$(VERSION)/doc/manual/manual.xml \
@@ -31,10 +32,21 @@ dist:
 		$(PACKAGE)-$(VERSION)/project.conf
 	$(RM) -- $(PACKAGE)-$(VERSION)
 
+distcheck: dist
+	$(TAR) -xzvf $(PACKAGE)-$(VERSION).tar.gz
+	$(MKDIR) -- $(PACKAGE)-$(VERSION)/objdir
+	$(MKDIR) -- $(PACKAGE)-$(VERSION)/destdir
+	(cd "$(PACKAGE)-$(VERSION)" && $(MAKE) OBJDIR="$$PWD/objdir/")
+	(cd "$(PACKAGE)-$(VERSION)" && $(MAKE) OBJDIR="$$PWD/objdir/" DESTDIR="$$PWD/destdir" install)
+	(cd "$(PACKAGE)-$(VERSION)" && $(MAKE) OBJDIR="$$PWD/objdir/" DESTDIR="$$PWD/destdir" uninstall)
+	(cd "$(PACKAGE)-$(VERSION)" && $(MAKE) OBJDIR="$$PWD/objdir/" distclean)
+	(cd "$(PACKAGE)-$(VERSION)" && $(MAKE) dist)
+	$(RM) -r -- $(PACKAGE)-$(VERSION)
+
 install:
 	@for i in $(SUBDIRS); do (cd "$$i" && $(MAKE) install) || exit; done
 
 uninstall:
 	@for i in $(SUBDIRS); do (cd "$$i" && $(MAKE) uninstall) || exit; done
 
-.PHONY: all subdirs clean distclean dist install uninstall
+.PHONY: all subdirs clean distclean dist distcheck install uninstall
diff --git a/doc/Makefile b/doc/Makefile
index 97f7ef7..58cc3ce 100644
--- a/doc/Makefile
+++ b/doc/Makefile
@@ -1,4 +1,5 @@
-TARGETS	= manual/manual.html
+TARGETS	= $(OBJDIR)manual/manual.html
+OBJDIR	=
 PREFIX	= /usr/local
 DESTDIR	=
 RM	= rm -f
@@ -9,8 +10,8 @@ INSTALL	= install
 
 all: $(TARGETS)
 
-manual/manual.html: manual/manual.xml manual/manual.xsl ../config.sh
-	./docbook.sh -P "$(PREFIX)" -- "manual/manual.html"
+$(OBJDIR)manual/manual.html: manual/manual.xml manual/manual.xsl ../config.sh
+	./docbook.sh -P "$(PREFIX)" -- "$(OBJDIR)manual/manual.html"
 
 clean:
 	$(RM) -- $(manual/manual.html_OBJS)
diff --git a/doc/docbook.sh b/doc/docbook.sh
index 0caaa39..fda4e2d 100755
--- a/doc/docbook.sh
+++ b/doc/docbook.sh
@@ -27,6 +27,7 @@
 #variables
 PREFIX="/usr/local"
 [ -f "../config.sh" ] && . "../config.sh"
+PROGNAME="docbook.sh"
 #executables
 DEBUG="_debug"
 FOP="fop"
@@ -52,17 +53,24 @@ _docbook()
 	target="$1"
 
 	source="${target%.*}.xml"
+	[ -f "$source" ] || source="${source#$OBJDIR}"
 	ext="${target##*.}"
 	ext="${ext##.}"
 	case "$ext" in
 		html)
 			XSL="http://docbook.sourceforge.net/release/xsl/current/xhtml/docbook.xsl"
+			[ -f "${source%.*}.xsl" ] && XSL="${source%.*}.xsl"
 			[ -f "${target%.*}.xsl" ] && XSL="${target%.*}.xsl"
-			[ -f "${target%.*}.css.xml" ] && XSLTPROC="$XSLTPROC --param custom.css.source \"${target%.*}.css.xml\" --param generate.css.header 1"
+			if [ -f "${target%.*}.css.xml" ]; then
+				XSLTPROC="$XSLTPROC --param custom.css.source \"${target%.*}.css.xml\" --param generate.css.header 1"
+			elif [ -f "${source%.*}.css.xml" ]; then
+				XSLTPROC="$XSLTPROC --param custom.css.source \"${source%.*}.css.xml\" --param generate.css.header 1"
+			fi
 			$DEBUG $XSLTPROC -o "$target" "$XSL" "$source"
 			;;
 		pdf)
 			XSL="http://docbook.sourceforge.net/release/xsl/current/fo/docbook.xsl"
+			[ -f "${source%.*}.xsl" ] && XSL="${source%.*}.xsl"
 			[ -f "${target%.*}.xsl" ] && XSL="${target%.*}.xsl"
 			$DEBUG $XSLTPROC -o "${target%.*}.fo" "$XSL" "$source" &&
 			$DEBUG $FOP -fo "${target%.*}.fo" -pdf "$target"
@@ -73,13 +81,13 @@ _docbook()
 			$DEBUG $XSLTPROC -o "$target" "$XSL" "$source"
 			;;
 		*)
-			echo "$0: $target: Unknown type" 1>&2
+			_error "$target: Unknown type"
 			return 2
 			;;
 	esac
 
 	if [ $? -ne 0 ]; then
-		echo "$0: $target: Could not create page" 1>&2
+		_error "$target: Could not create page"
 		$RM -- "$target"
 		return 2
 	fi
@@ -89,7 +97,7 @@ _docbook()
 #error
 _error()
 {
-	echo "docbook.sh: $@" 1>&2
+	echo "$PROGNAME: $@" 1>&2
 	return 2
 }
 
@@ -97,7 +105,7 @@ _error()
 #usage
 _usage()
 {
-	echo "Usage: docbook.sh [-c|-i|-u][-P prefix] target..." 1>&2
+	echo "Usage: $PROGNAME [-c|-i|-u][-P prefix] target..." 1>&2
 	return 1
 }
 
@@ -153,7 +161,8 @@ while [ $# -gt 0 ]; do
 	case "$ext" in
 		html)
 			instdir="$DATADIR/doc/$ext/$PACKAGE"
-			source="${target%.*}.xml"
+			source="${target#$OBJDIR}"
+			source="${source%.*}.xml"
 			xpath="string(/refentry/refmeta/manvolnum)"
 			section=$($XMLLINT --xpath "$xpath" "$source")
 			if [ $? -eq 0 -a -n "$section" ]; then
@@ -167,7 +176,7 @@ while [ $# -gt 0 ]; do
 			instdir="$MANDIR/man$ext"
 			;;
 		*)
-			echo "$0: $target: Unknown type" 1>&2
+			_error "$target: Unknown type"
 			exit 2
 			;;
 	esac
@@ -177,14 +186,16 @@ while [ $# -gt 0 ]; do
 
 	#uninstall
 	if [ "$uninstall" -eq 1 ]; then
+		target="${target#$OBJDIR}"
 		$DEBUG $RM -- "$instdir/$target"		|| exit 2
 		continue
 	fi
 
 	#install
 	if [ "$install" -eq 1 ]; then
+		source="${target#$OBJDIR}"
 		$DEBUG $MKDIR -- "$instdir"			|| exit 2
-		$DEBUG $INSTALL "$target" "$instdir/$target"	|| exit 2
+		$DEBUG $INSTALL "$target" "$instdir/$source"	|| exit 2
 		continue
 	fi