diff --git a/cmd/chroma/main.go b/cmd/chroma/main.go
index b57fc3a..ff79929 100644
--- a/cmd/chroma/main.go
+++ b/cmd/chroma/main.go
@@ -44,9 +44,9 @@ command, for Go.
 		Check      bool             `help:"Do not format, check for tokenization errors instead."`
 		Filename   string           `help:"Filename to use for selecting a lexer when reading from stdin."`
 
-		Lexer     string `help:"Lexer to use when formatting." placeholder:"autodetect" short:"l"`
-		Style     string `help:"Style to use for formatting." default:"swapoff" short:"s"`
-		Formatter string `help:"Formatter to use." default:"terminal" short:"f"`
+		Lexer     string `help:"Lexer to use when formatting." default:"autodetect" short:"l" enum:"${lexers}"`
+		Style     string `help:"Style to use for formatting." default:"swapoff" short:"s" enum:"${styles}"`
+		Formatter string `help:"Formatter to use." default:"terminal" short:"f" enum:"${formatters}"`
 
 		JSON bool `help:"Output JSON representation of tokens."`
 
@@ -79,7 +79,10 @@ func (n *nopFlushableWriter) Flush() error { return nil }
 
 func main() {
 	ctx := kong.Parse(&cli, kong.Description(description), kong.Vars{
-		"version": fmt.Sprintf("%s-%s-%s", version, commit, date),
+		"version":    fmt.Sprintf("%s-%s-%s", version, commit, date),
+		"lexers":     "autodetect," + strings.Join(lexers.Names(true), ","),
+		"styles":     strings.Join(styles.Names(), ","),
+		"formatters": strings.Join(formatters.Names(), ","),
 	})
 	if cli.List {
 		listAll()
@@ -246,7 +249,7 @@ func lex(ctx *kong.Context, path string, contents string) chroma.Iterator {
 }
 
 func selexer(path, contents string) (lexer chroma.Lexer) {
-	if cli.Lexer != "" {
+	if cli.Lexer != "autodetect" {
 		return lexers.Get(cli.Lexer)
 	}
 	if path != "" {
diff --git a/go.mod b/go.mod
index f664c66..281cf3e 100644
--- a/go.mod
+++ b/go.mod
@@ -4,8 +4,8 @@ require (
 	github.com/GeertJohan/go.rice v1.0.0
 	github.com/alecthomas/assert v0.0.0-20170929043011-405dbfeb8e38
 	github.com/alecthomas/colour v0.0.0-20160524082231-60882d9e2721 // indirect
-	github.com/alecthomas/kong v0.1.15
-	github.com/alecthomas/kong-hcl v0.1.7
+	github.com/alecthomas/kong v0.2.1-0.20190708041108-0548c6b1afae
+	github.com/alecthomas/kong-hcl v0.1.8-0.20190615233001-b21fea9723c8
 	github.com/alecthomas/repr v0.0.0-20180818092828-117648cd9897 // indirect
 	github.com/danwakefield/fnmatch v0.0.0-20160403171240-cbb64ac3d964
 	github.com/dlclark/regexp2 v1.1.6
diff --git a/go.sum b/go.sum
index 66ffcc9..2638362 100644
--- a/go.sum
+++ b/go.sum
@@ -6,11 +6,11 @@ github.com/alecthomas/colour v0.0.0-20160524082231-60882d9e2721 h1:JHZL0hZKJ1VEN
 github.com/alecthomas/colour v0.0.0-20160524082231-60882d9e2721/go.mod h1:QO9JBoKquHd+jz9nshCh40fOfO+JzsoXy8qTHF68zU0=
 github.com/alecthomas/go.rice v1.0.1-0.20190717041731-572a5da3dff8 h1:PyEz5JLcmLYoi+1CegL90Wm5qfx9pl62D/DeNRnmkdU=
 github.com/alecthomas/go.rice v1.0.1-0.20190717041731-572a5da3dff8/go.mod h1:af5vUNlDNkCjOZeSGFgIJxDje9qdjsO6hshx0gTmZt4=
-github.com/alecthomas/kong v0.1.13/go.mod h1:0m2VYms8rH0qbCqVB2gvGHk74bqLIq0HXjCs5bNbNQU=
-github.com/alecthomas/kong v0.1.15 h1:IWBg+KrLvoHBicD50OzMI8fKjrtAa1okMR9g38HVM/s=
-github.com/alecthomas/kong v0.1.15/go.mod h1:0m2VYms8rH0qbCqVB2gvGHk74bqLIq0HXjCs5bNbNQU=
-github.com/alecthomas/kong-hcl v0.1.7 h1:BhqAe2mE/cBq7Plnb218eTonsp4KcXf0BZCu3bO3qxg=
-github.com/alecthomas/kong-hcl v0.1.7/go.mod h1:+diJg0tzfMUY/5uDo0dlb7uThhVpWr59PuYkdtRJbms=
+github.com/alecthomas/kong v0.1.17-0.20190424132513-439c674f7ae0/go.mod h1:+inYUSluD+p4L8KdviBSgzcqEjUQOfC5fQDRFuc36lI=
+github.com/alecthomas/kong v0.2.1-0.20190708041108-0548c6b1afae h1:C4Q9m+oXOxcSWwYk9XzzafY2xAVAaeubZbUHJkw3PlY=
+github.com/alecthomas/kong v0.2.1-0.20190708041108-0548c6b1afae/go.mod h1:+inYUSluD+p4L8KdviBSgzcqEjUQOfC5fQDRFuc36lI=
+github.com/alecthomas/kong-hcl v0.1.8-0.20190615233001-b21fea9723c8 h1:atLL+K8Hg0e8863K2X+k7qu+xz3M2a/mWFIACAPf55M=
+github.com/alecthomas/kong-hcl v0.1.8-0.20190615233001-b21fea9723c8/go.mod h1:MRgZdU3vrFd05IQ89AxUZ0aYdF39BYoNFa324SodPCA=
 github.com/alecthomas/repr v0.0.0-20180818092828-117648cd9897 h1:p9Sln00KOTlrYkxI1zYWl1QLnEqAqEARBEYa8FQnQcY=
 github.com/alecthomas/repr v0.0.0-20180818092828-117648cd9897/go.mod h1:xTS7Pm1pD1mvyM075QCDSRqH6qRLXylzS24ZTpRiSzQ=
 github.com/daaku/go.zipexe v1.0.0 h1:VSOgZtH418pH9L16hC/JrgSNJbbAL26pj7lmD1+CGdY=
@@ -37,9 +37,12 @@ github.com/mattn/go-colorable v0.0.9 h1:UVL0vNpWh04HeJXV0KLcaT7r06gOH2l4OW6ddYRU
 github.com/mattn/go-colorable v0.0.9/go.mod h1:9vuHe8Xs5qXnSaW/c/ABM9alt+Vo+STaOChaDxuIBZU=
 github.com/mattn/go-isatty v0.0.4 h1:bnP0vzxcAdeI1zdubAl5PjU6zsERjGZb7raWodagDYs=
 github.com/mattn/go-isatty v0.0.4/go.mod h1:M+lRXTBqGeGNdLjl/ufCoiOlB5xdOkqRJdNxMWT7Zi4=
+github.com/mitchellh/mapstructure v1.1.2/go.mod h1:FVVH3fgwuzCH5S8UJGiWEs2h04kUh9fWfEaFds41c1Y=
 github.com/nkovacs/streamquote v1.0.0/go.mod h1:BN+NaZ2CmdKqUuTUXUEm9j95B2TRbpOWpxbJYzzgUsc=
 github.com/pkg/errors v0.8.0 h1:WdK/asTD0HN+q6hsWO3/vpuAkAr+tw6aNJNDFFf0+qw=
 github.com/pkg/errors v0.8.0/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
+github.com/pkg/errors v0.8.1 h1:iURUrRGxPUNPdy5/HRSm+Yj6okJ6UtLINN0Q9M4+h3I=
+github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/sergi/go-diff v1.0.0 h1:Kpca3qRNrduNnOQeazBd0ysaKrUJiIuISHxogkT9RPQ=