diff --git a/GNUmakefile b/GNUmakefile
index 2eef88e..d1be774 100644
--- a/GNUmakefile
+++ b/GNUmakefile
@@ -1,7 +1,8 @@
-PROG=	doas
-MAN=	doas.1 doas.conf.5
+PROG=		doas
+MAN=		doas.1 doas.conf.5
+COMPLETION=	doas.completion
 
-SRCS=	parse.y doas.c env.c
+SRCS=		parse.y doas.c env.c
 
 include config.mk
 
@@ -19,17 +20,20 @@ install: ${PROG} ${MAN}
 	mkdir -p -m 0755 ${DESTDIR}${BINDIR}
 	mkdir -p -m 0755 ${DESTDIR}${MANDIR}/man1
 	mkdir -p -m 0755 ${DESTDIR}${MANDIR}/man5
+	mkdir -p -m 0755 ${DESTDIR}${COMPDIR}/completions
 	cp -f ${PROG} ${DESTDIR}${BINDIR}
 	chown ${BINOWN}:${BINGRP} ${DESTDIR}${BINDIR}/${PROG}
 	chmod ${BINMODE} ${DESTDIR}${BINDIR}/${PROG}
 	cp -f doas.1 ${DESTDIR}${MANDIR}/man1
 	cp -f doas.conf.5 ${DESTDIR}${MANDIR}/man5
+	cp -f doas.completion ${DESTDIR}${COMPDIR}/completions/doas
 
 uninstall:
 	rm -f ${DESTDIR}${BINDIR}/${PROG}
 	rm -f ${DESTDIR}${PAMDIR}/doas
 	rm -f ${DESTDIR}${MANDIR}/man1/doas.1
 	rm -f ${DESTDIR}${MANDIR}/man5/doas.conf.5
+	rm -f ${DESTDIR}${COMPDIR}/completions/doas
 
 clean:
 	rm -f ${PROG} ${OBJS} ${OBJS:.o=.d} parse.c
diff --git a/configure b/configure
index 1f92f01..62e4503 100755
--- a/configure
+++ b/configure
@@ -14,6 +14,7 @@ usage: configure [options]
   --bindir=DIR           user executables [PREFIX/bin]
   --datadir=DIR          architecture-independent data files [PREFIX/share]
   --mandir=DIR           manual pages [DATADIR/man]
+  --compdir=DIR          bash completions [DATADIR/bash-completion]
   --sysconfdir=DIR       directory for configuration files [/etc]
 
   --build=build-alias    a cpu-vendor-opsys for the system where the application will be built
@@ -50,6 +51,7 @@ for x; do
 	--bindir) BINDIR=$var ;;
 	--datadir) SHAREDIR=$var ;;
 	--mandir) MANDIR=$var ;;
+	--compdir) COMPDIR=$var ;;
 	--sysconfdir) SYSCONFDIR=$var ;;
 	--build) BUILD=$var ;;
 	--host) HOST=$var ;;
@@ -131,6 +133,7 @@ esac
 : ${BINDIR:=${PREFIX}/bin}
 : ${SHAREDIR:=${PREFIX}/share}
 : ${MANDIR:=${SHAREDIR}/man}
+: ${COMPDIR:=${SHAREDIR}/bash-completion}
 : ${SYSCONFDIR:=/etc}
 : ${BINMODE:=4755}
 : ${BINOWN:=root}
@@ -142,6 +145,7 @@ EPREFIX  ?=	${EPREFIX}
 BINDIR   ?=	${BINDIR}
 SHAREDIR ?=	${SHAREDIR}
 MANDIR   ?=	${MANDIR}
+COMPDIR  ?=	${COMPDIR}
 SYSCONFDIR?=	${SYSCONFDIR}
 BINMODE  ?=	${BINMODE}
 BINOWN  ?=	${BINOWN}
diff --git a/doas.completion b/doas.completion
new file mode 100644
index 0000000..e11c3d6
--- /dev/null
+++ b/doas.completion
@@ -0,0 +1,19 @@
+# bash completion for doas(1)                              -*- shell-script -*-
+
+_doas() {
+	local cur prev words cword split
+	_init_completion -s || return
+
+	for ((i = 1; i <= cword; i++)); do
+		if [[ ${words[i]} != -* ]]; then
+			local PATH=$PATH:/sbin:/usr/sbin:/usr/local/sbin
+			local root_command=${words[i]}
+			_command_offset $i
+			return
+		fi
+
+		[[ ${words[i]} == -@(u|C) ]] && ((i++))
+	done
+} && complete -F _doas doas
+
+# ex: filetype=sh