diff --git a/volume/Makefile b/volume/Makefile
deleted file mode 100644
index 2ef1425..0000000
--- a/volume/Makefile
+++ /dev/null
@@ -1,20 +0,0 @@
-all: ;
-clean: ;
-sane: ;
-
-dist: ../dist/volume.tar.gz
-
-../dist/volume: volume
-	mkdir -p ../dist/volume.tmp/bin/
-	cp volume* ../dist/volume.tmp/bin/
-	mv ../dist/volume.tmp ../dist/volume
-
-../dist/volume.tar: ../dist/volume
-	cd ../dist/volume && pax -w -x ustar . >../volume.tar.tmp
-	mv ../dist/volume.tar.tmp ../dist/volume.tar
-
-../dist/volume.tar.gz: ../dist/volume.tar
-	gzip -c <../dist/volume.tar >../dist/volume.tar.gz.tmp
-	mv ../dist/volume.tar.gz.tmp ../dist/volume.tar.gz
-	
-.PHONY: all clean sane
diff --git a/volume/volume b/volume/volume
index 7973459..be5f6fa 100755
--- a/volume/volume
+++ b/volume/volume
@@ -15,7 +15,7 @@ argv0="$0"
 
 VOLUME_TMP_FILE="$HOME/.volume-previous"
 
-if [ "$(uname)" = NetBSD ]; then
+if streq "$(uname)" NetBSD; then
 	VOLUME_SYSTEM=netbsd
 elif command -v pactl >/dev/null 2>&1; then
 	VOLUME_SYSTEM=pulseaudio
@@ -52,12 +52,12 @@ case "$1" in
 -) "$0" r -"$2" ;;
 
 a*)
-	nonzero $2 && ! nonzero $3 && str isdigit "$2" \
+	str isvalue $2 && ! str isvalue $3 && str isdigit "$2" \
 		|| usage
 	"$0".$VOLUME_SYSTEM "$@"
 	;;
 s*)
-	! nonzero $2 \
+	! str isvalue $2 \
 		|| usage
 	"$0".$VOLUME_SYSTEM s
 	;;
@@ -68,9 +68,9 @@ d*)
 		$VOLUME_SYSTEM
 	;;
 
-m*) [ -z "$2" ] || usage
+m*) ! str isvalue "$2" || usage
 	# restore previous volume if there is one
-	if [ -e "$VOLUME_TMP_FILE" ]; then
+	if test -e "$VOLUME_TMP_FILE"; then
 		xargs "$0" a <"$VOLUME_TMP_FILE" \
 			&& rm "$VOLUME_TMP_FILE" \
 			&& printf "Unmuted.\n" \
@@ -98,7 +98,7 @@ m*) [ -z "$2" ] || usage
 	exit 0 ;;
 
 r*)
-	nonzero $2 && ! nonzero $3 \
+	str isvalue $2 && ! str isvalue $3 \
 			&& str isdigit "$(printf "%s\n" "$2" | sed 's/^\-//')" \
 		|| usage