diff --git a/command.go b/command.go
index 542dfff..9d10dfe 100644
--- a/command.go
+++ b/command.go
@@ -296,10 +296,16 @@ func copyFlagSetWithout(fs *pflag.FlagSet, without string) *pflag.FlagSet {
 }
 
 func (inv *Invocation) CurWords() (prev string, cur string) {
-	if len(inv.Args) == 1 {
+	switch len(inv.Args) {
+	// All the shells we support will supply at least one argument (empty string),
+	// but we don't want to panic.
+	case 0:
+		cur = ""
+		prev = ""
+	case 1:
 		cur = inv.Args[0]
 		prev = ""
-	} else {
+	default:
 		cur = inv.Args[len(inv.Args)-1]
 		prev = inv.Args[len(inv.Args)-2]
 	}
@@ -645,9 +651,13 @@ func (inv *Invocation) completeFlag(word string) []string {
 	if opt.CompletionHandler != nil {
 		return opt.CompletionHandler(inv)
 	}
-	val, ok := opt.Value.(*Enum)
+	enum, ok := opt.Value.(*Enum)
+	if ok {
+		return enum.Choices
+	}
+	enumArr, ok := opt.Value.(*EnumArray)
 	if ok {
-		return val.Choices
+		return enumArr.Choices
 	}
 	return nil
 }
diff --git a/command_test.go b/command_test.go
index de6c12d..41541f4 100644
--- a/command_test.go
+++ b/command_test.go
@@ -34,14 +34,15 @@ func fakeIO(i *serpent.Invocation) *ioBufs {
 func sampleCommand(t *testing.T) *serpent.Command {
 	t.Helper()
 	var (
-		verbose bool
-		lower   bool
-		prefix  string
-		reqBool bool
-		reqStr  string
-		reqArr  []string
-		fileArr []string
-		enumStr string
+		verbose    bool
+		lower      bool
+		prefix     string
+		reqBool    bool
+		reqStr     string
+		reqArr     []string
+		reqEnumArr []string
+		fileArr    []string
+		enumStr    string
 	)
 	enumChoices := []string{"foo", "bar", "qux"}
 	return &serpent.Command{
@@ -94,6 +95,11 @@ func sampleCommand(t *testing.T) *serpent.Command {
 						FlagShorthand: "a",
 						Value:         serpent.StringArrayOf(&reqArr),
 					},
+					serpent.Option{
+						Name:  "req-enum-array",
+						Flag:  "req-enum-array",
+						Value: serpent.EnumArrayOf(&reqEnumArr, enumChoices...),
+					},
 				},
 				HelpHandler: func(i *serpent.Invocation) error {
 					_, _ = i.Stdout.Write([]byte("help text.png"))
diff --git a/completion.go b/completion.go
index a0fb779..1da93a0 100644
--- a/completion.go
+++ b/completion.go
@@ -1,5 +1,9 @@
 package serpent
 
+import (
+	"github.com/spf13/pflag"
+)
+
 // CompletionModeEnv is a special environment variable that is
 // set when the command is being run in completion mode.
 const CompletionModeEnv = "COMPLETION_MODE"
@@ -10,15 +14,18 @@ func (inv *Invocation) IsCompletionMode() bool {
 	return ok
 }
 
-// DefaultCompletionHandler returns a handler that prints all
-// known flags and subcommands that haven't already been set to valid values.
+// DefaultCompletionHandler is a handler that prints all  known flags and
+// subcommands that haven't been exhaustively set.
 func DefaultCompletionHandler(inv *Invocation) []string {
 	var allResps []string
 	for _, cmd := range inv.Command.Children {
 		allResps = append(allResps, cmd.Name())
 	}
 	for _, opt := range inv.Command.Options {
-		if opt.ValueSource == ValueSourceNone || opt.ValueSource == ValueSourceDefault || opt.Value.Type() == "string-array" {
+		_, isSlice := opt.Value.(pflag.SliceValue)
+		if opt.ValueSource == ValueSourceNone ||
+			opt.ValueSource == ValueSourceDefault ||
+			isSlice {
 			allResps = append(allResps, "--"+opt.Flag)
 		}
 	}
diff --git a/completion/all.go b/completion/all.go
index b20c254..ca6e2cf 100644
--- a/completion/all.go
+++ b/completion/all.go
@@ -1,60 +1,77 @@
 package completion
 
 import (
+	"bytes"
+	"errors"
 	"fmt"
 	"io"
+	"io/fs"
 	"os"
 	"os/user"
 	"path/filepath"
+	"runtime"
 	"strings"
 	"text/template"
 
 	"github.com/coder/serpent"
+
+	"github.com/natefinch/atomic"
 )
 
 const (
-	BashShell  string = "bash"
-	FishShell  string = "fish"
-	ZShell     string = "zsh"
-	Powershell string = "powershell"
+	completionStartTemplate = `# ============ BEGIN {{.Name}} COMPLETION ============`
+	completionEndTemplate   = `# ============ END {{.Name}} COMPLETION ==============`
 )
 
-var shellCompletionByName = map[string]func(io.Writer, string) error{
-	BashShell:  generateCompletion(bashCompletionTemplate),
-	FishShell:  generateCompletion(fishCompletionTemplate),
-	ZShell:     generateCompletion(zshCompletionTemplate),
-	Powershell: generateCompletion(pshCompletionTemplate),
+type Shell interface {
+	Name() string
+	InstallPath() (string, error)
+	WriteCompletion(io.Writer) error
+	ProgramName() string
 }
 
-func ShellOptions(choice *string) *serpent.Enum {
-	return serpent.EnumOf(choice, BashShell, FishShell, ZShell, Powershell)
-}
+const (
+	ShellBash       string = "bash"
+	ShellFish       string = "fish"
+	ShellZsh        string = "zsh"
+	ShellPowershell string = "powershell"
+)
 
-func WriteCompletion(writer io.Writer, shell string, cmdName string) error {
-	fn, ok := shellCompletionByName[shell]
-	if !ok {
-		return fmt.Errorf("unknown shell %q", shell)
+func ShellByName(shell, programName string) (Shell, error) {
+	switch shell {
+	case ShellBash:
+		return Bash(runtime.GOOS, programName), nil
+	case ShellFish:
+		return Fish(runtime.GOOS, programName), nil
+	case ShellZsh:
+		return Zsh(runtime.GOOS, programName), nil
+	case ShellPowershell:
+		return Powershell(runtime.GOOS, programName), nil
+	default:
+		return nil, fmt.Errorf("unsupported shell %q", shell)
 	}
-	fn(writer, cmdName)
-	return nil
 }
 
-func DetectUserShell() (string, error) {
+func ShellOptions(choice *string) *serpent.Enum {
+	return serpent.EnumOf(choice, ShellBash, ShellFish, ShellZsh, ShellPowershell)
+}
+
+func DetectUserShell(programName string) (Shell, error) {
 	// Attempt to get the SHELL environment variable first
 	if shell := os.Getenv("SHELL"); shell != "" {
-		return filepath.Base(shell), nil
+		return ShellByName(filepath.Base(shell), "")
 	}
 
 	// Fallback: Look up the current user and parse /etc/passwd
 	currentUser, err := user.Current()
 	if err != nil {
-		return "", err
+		return nil, err
 	}
 
 	// Open and parse /etc/passwd
 	passwdFile, err := os.ReadFile("/etc/passwd")
 	if err != nil {
-		return "", err
+		return nil, err
 	}
 
 	lines := strings.Split(string(passwdFile), "\n")
@@ -62,33 +79,120 @@ func DetectUserShell() (string, error) {
 		if strings.HasPrefix(line, currentUser.Username+":") {
 			parts := strings.Split(line, ":")
 			if len(parts) > 6 {
-				return filepath.Base(parts[6]), nil // The shell is typically the 7th field
+				return ShellByName(filepath.Base(parts[6]), programName) // The shell is typically the 7th field
 			}
 		}
 	}
 
-	return "", fmt.Errorf("default shell not found")
+	return nil, fmt.Errorf("default shell not found")
 }
 
-func generateCompletion(
-	scriptTemplate string,
-) func(io.Writer, string) error {
-	return func(w io.Writer, rootCmdName string) error {
-		tmpl, err := template.New("script").Parse(scriptTemplate)
-		if err != nil {
-			return fmt.Errorf("parse template: %w", err)
-		}
+func writeConfig(
+	w io.Writer,
+	cfgTemplate string,
+	programName string,
+) error {
+	tmpl, err := template.New("script").Parse(cfgTemplate)
+	if err != nil {
+		return fmt.Errorf("parse template: %w", err)
+	}
 
-		err = tmpl.Execute(
-			w,
-			map[string]string{
-				"Name": rootCmdName,
-			},
-		)
-		if err != nil {
-			return fmt.Errorf("execute template: %w", err)
-		}
+	err = tmpl.Execute(
+		w,
+		map[string]string{
+			"Name": programName,
+		},
+	)
+	if err != nil {
+		return fmt.Errorf("execute template: %w", err)
+	}
+
+	return nil
+}
+
+func InstallShellCompletion(shell Shell) error {
+	path, err := shell.InstallPath()
+	if err != nil {
+		return fmt.Errorf("get install path: %w", err)
+	}
+	var headerBuf bytes.Buffer
+	err = writeConfig(&headerBuf, completionStartTemplate, shell.ProgramName())
+	if err != nil {
+		return fmt.Errorf("generate header: %w", err)
+	}
+
+	var footerBytes bytes.Buffer
+	err = writeConfig(&footerBytes, completionEndTemplate, shell.ProgramName())
+	if err != nil {
+		return fmt.Errorf("generate footer: %w", err)
+	}
 
-		return nil
+	err = os.MkdirAll(filepath.Dir(path), 0o755)
+	if err != nil {
+		return fmt.Errorf("create directories: %w", err)
+	}
+
+	f, err := os.ReadFile(path)
+	if err != nil && !errors.Is(err, fs.ErrNotExist) {
+		return fmt.Errorf("read ssh config failed: %w", err)
+	}
+
+	before, after, err := templateConfigSplit(headerBuf.Bytes(), footerBytes.Bytes(), f)
+	if err != nil {
+		return err
+	}
+
+	outBuf := bytes.Buffer{}
+	_, _ = outBuf.Write(before)
+	if len(before) > 0 {
+		_, _ = outBuf.Write([]byte("\n"))
+	}
+	_, _ = outBuf.Write(headerBuf.Bytes())
+	err = shell.WriteCompletion(&outBuf)
+	if err != nil {
+		return fmt.Errorf("generate completion: %w", err)
+	}
+	_, _ = outBuf.Write(footerBytes.Bytes())
+	_, _ = outBuf.Write([]byte("\n"))
+	_, _ = outBuf.Write(after)
+
+	err = atomic.WriteFile(path, &outBuf)
+	if err != nil {
+		return fmt.Errorf("write completion: %w", err)
+	}
+
+	return nil
+}
+
+func templateConfigSplit(header, footer, data []byte) (before, after []byte, err error) {
+	startCount := bytes.Count(data, header)
+	endCount := bytes.Count(data, footer)
+	if startCount > 1 || endCount > 1 {
+		return nil, nil, fmt.Errorf("Malformed config file: multiple config sections")
+	}
+
+	startIndex := bytes.Index(data, header)
+	endIndex := bytes.Index(data, footer)
+	if startIndex == -1 && endIndex != -1 {
+		return data, nil, fmt.Errorf("Malformed config file: missing completion header")
+	}
+	if startIndex != -1 && endIndex == -1 {
+		return data, nil, fmt.Errorf("Malformed config file: missing completion footer")
+	}
+	if startIndex != -1 && endIndex != -1 {
+		if startIndex > endIndex {
+			return data, nil, fmt.Errorf("Malformed config file: completion header after footer")
+		}
+		// Include leading and trailing newline, if present
+		start := startIndex
+		if start > 0 {
+			start--
+		}
+		end := endIndex + len(footer)
+		if end < len(data) {
+			end++
+		}
+		return data[:start], data[end:], nil
 	}
+	return data, nil, nil
 }
diff --git a/completion/bash.go b/completion/bash.go
index fad4069..14282eb 100644
--- a/completion/bash.go
+++ b/completion/bash.go
@@ -1,22 +1,62 @@
 package completion
 
+import (
+	"io"
+	"path/filepath"
+
+	home "github.com/mitchellh/go-homedir"
+)
+
+type bash struct {
+	goos        string
+	programName string
+}
+
+var _ Shell = &bash{}
+
+func Bash(goos string, programName string) Shell {
+	return &bash{goos: goos, programName: programName}
+}
+
+func (b *bash) Name() string {
+	return "bash"
+}
+
+func (b *bash) InstallPath() (string, error) {
+	homeDir, err := home.Dir()
+	if err != nil {
+		return "", err
+	}
+	if b.goos == "darwin" {
+		return filepath.Join(homeDir, ".bash_profile"), nil
+	}
+	return filepath.Join(homeDir, ".bashrc"), nil
+}
+
+func (b *bash) WriteCompletion(w io.Writer) error {
+	return writeConfig(w, bashCompletionTemplate, b.programName)
+}
+
+func (b *bash) ProgramName() string {
+	return b.programName
+}
+
 const bashCompletionTemplate = `
 _generate_{{.Name}}_completions() {
-    # Capture the line excluding the command, and everything after the current word
     local args=("${COMP_WORDS[@]:1:COMP_CWORD}")
 
-    # Set COMPLETION_MODE and call the command with the arguments, capturing the output
-    local completions=$(COMPLETION_MODE=1 "{{.Name}}" "${args[@]}")
+    declare -a output
+    mapfile -t output < <(COMPLETION_MODE=1 "{{.Name}}" "${args[@]}")
 
-    # Use the command's output to generate completions for the current word
-    COMPREPLY=($(compgen -W "$completions" -- "${COMP_WORDS[COMP_CWORD]}"))
+    declare -a completions
+    mapfile -t completions < <( compgen -W "$(printf '%q ' "${output[@]}")" -- "$2" )
 
-    # Ensure no files are shown, even if there are no matches
-    if [ ${#COMPREPLY[@]} -eq 0 ]; then
-        COMPREPLY=()
-    fi
+    local comp
+    COMPREPLY=()
+    for comp in "${completions[@]}"; do
+        COMPREPLY+=("$(printf "%q" "$comp")")
+    done
 }
-
 # Setup Bash to use the function for completions for '{{.Name}}'
 complete -F _generate_{{.Name}}_completions {{.Name}}
 `
diff --git a/completion/fish.go b/completion/fish.go
index f9b2793..7e5a21e 100644
--- a/completion/fish.go
+++ b/completion/fish.go
@@ -1,5 +1,43 @@
 package completion
 
+import (
+	"io"
+	"path/filepath"
+
+	home "github.com/mitchellh/go-homedir"
+)
+
+type fish struct {
+	goos        string
+	programName string
+}
+
+var _ Shell = &fish{}
+
+func Fish(goos string, programName string) Shell {
+	return &fish{goos: goos, programName: programName}
+}
+
+func (f *fish) Name() string {
+	return "fish"
+}
+
+func (f *fish) InstallPath() (string, error) {
+	homeDir, err := home.Dir()
+	if err != nil {
+		return "", err
+	}
+	return filepath.Join(homeDir, ".config/fish/completions/", f.programName+".fish"), nil
+}
+
+func (f *fish) WriteCompletion(w io.Writer) error {
+	return writeConfig(w, fishCompletionTemplate, f.programName)
+}
+
+func (f *fish) ProgramName() string {
+	return f.programName
+}
+
 const fishCompletionTemplate = `
 function _{{.Name}}_completions
 	# Capture the full command line as an array
diff --git a/completion/powershell.go b/completion/powershell.go
index e30c61b..cc083bd 100644
--- a/completion/powershell.go
+++ b/completion/powershell.go
@@ -1,7 +1,52 @@
 package completion
 
-const pshCompletionTemplate = `
+import (
+	"io"
+	"os/exec"
+	"strings"
+)
+
+type powershell struct {
+	goos        string
+	programName string
+}
+
+var _ Shell = &powershell{}
+
+func (p *powershell) Name() string {
+	return "powershell"
+}
+
+func Powershell(goos string, programName string) Shell {
+	return &powershell{goos: goos, programName: programName}
+}
 
+func (p *powershell) InstallPath() (string, error) {
+	var (
+		path []byte
+		err  error
+	)
+	cmd := "$PROFILE.CurrentUserAllHosts"
+	if p.goos == "windows" {
+		path, err = exec.Command("powershell", cmd).CombinedOutput()
+	} else {
+		path, err = exec.Command("pwsh", "-Command", cmd).CombinedOutput()
+	}
+	if err != nil {
+		return "", err
+	}
+	return strings.TrimSpace(string(path)), nil
+}
+
+func (p *powershell) WriteCompletion(w io.Writer) error {
+	return writeConfig(w, pshCompletionTemplate, p.programName)
+}
+
+func (p *powershell) ProgramName() string {
+	return p.programName
+}
+
+const pshCompletionTemplate = `
 # Escaping output sourced from:
 # https://github.com/spf13/cobra/blob/e94f6d0dd9a5e5738dca6bce03c4b1207ffbc0ec/powershell_completions.go#L47
 filter _{{.Name}}_escapeStringWithSpecialChars {
@@ -35,8 +80,7 @@ $_{{.Name}}_completions = {
     Invoke-Expression $Command | Where-Object { $_ -like "$wordToComplete*" } | ForEach-Object {
         "$_" | _{{.Name}}_escapeStringWithSpecialChars
     }
-    rm env:COMPLETION_MODE
+    $env:COMPLETION_MODE = ''
 }
-
 Register-ArgumentCompleter -CommandName {{.Name}} -ScriptBlock $_{{.Name}}_completions
 `
diff --git a/completion/zsh.go b/completion/zsh.go
index a8ee4a8..b2793b0 100644
--- a/completion/zsh.go
+++ b/completion/zsh.go
@@ -1,12 +1,49 @@
 package completion
 
+import (
+	"io"
+	"path/filepath"
+
+	home "github.com/mitchellh/go-homedir"
+)
+
+type zsh struct {
+	goos        string
+	programName string
+}
+
+var _ Shell = &zsh{}
+
+func Zsh(goos string, programName string) Shell {
+	return &zsh{goos: goos, programName: programName}
+}
+
+func (z *zsh) Name() string {
+	return "zsh"
+}
+
+func (z *zsh) InstallPath() (string, error) {
+	homeDir, err := home.Dir()
+	if err != nil {
+		return "", err
+	}
+	return filepath.Join(homeDir, ".zshrc"), nil
+}
+
+func (z *zsh) WriteCompletion(w io.Writer) error {
+	return writeConfig(w, zshCompletionTemplate, z.programName)
+}
+
+func (z *zsh) ProgramName() string {
+	return z.programName
+}
+
 const zshCompletionTemplate = `
 _{{.Name}}_completions() {
 	local -a args completions
 	args=("${words[@]:1:$#words}")
-	completions=($(COMPLETION_MODE=1 "{{.Name}}" "${args[@]}"))
+	completions=(${(f)"$(COMPLETION_MODE=1 "{{.Name}}" "${args[@]}")"})
 	compadd -a completions
 }
-
 compdef _{{.Name}}_completions {{.Name}}
 `
diff --git a/completion_test.go b/completion_test.go
index 5ca160a..f1527be 100644
--- a/completion_test.go
+++ b/completion_test.go
@@ -2,11 +2,14 @@ package serpent_test
 
 import (
 	"fmt"
+	"io"
 	"os"
+	"path/filepath"
 	"strings"
 	"testing"
 
 	serpent "github.com/coder/serpent"
+	"github.com/coder/serpent/completion"
 	"github.com/stretchr/testify/require"
 )
 
@@ -52,7 +55,7 @@ func TestCompletion(t *testing.T) {
 		io := fakeIO(i)
 		err := i.Run()
 		require.NoError(t, err)
-		require.Equal(t, "--req-array\n--req-bool\n--req-enum\n--req-string\n", io.Stdout.String())
+		require.Equal(t, "--req-array\n--req-bool\n--req-enum\n--req-enum-array\n--req-string\n", io.Stdout.String())
 	})
 
 	t.Run("ListFlagsAfterArg", func(t *testing.T) {
@@ -72,7 +75,7 @@ func TestCompletion(t *testing.T) {
 		io := fakeIO(i)
 		err := i.Run()
 		require.NoError(t, err)
-		require.Equal(t, "--req-array\n--req-enum\n", io.Stdout.String())
+		require.Equal(t, "--req-array\n--req-enum\n--req-enum-array\n", io.Stdout.String())
 	})
 
 	t.Run("FlagShorthand", func(t *testing.T) {
@@ -82,7 +85,7 @@ func TestCompletion(t *testing.T) {
 		io := fakeIO(i)
 		err := i.Run()
 		require.NoError(t, err)
-		require.Equal(t, "--req-array\n--req-enum\n", io.Stdout.String())
+		require.Equal(t, "--req-array\n--req-enum\n--req-enum-array\n", io.Stdout.String())
 	})
 
 	t.Run("NoOptDefValueFlag", func(t *testing.T) {
@@ -125,6 +128,36 @@ func TestCompletion(t *testing.T) {
 		require.Equal(t, "--req-enum=foo\n--req-enum=bar\n--req-enum=qux\n", io.Stdout.String())
 	})
 
+	t.Run("EnumArrayOK", func(t *testing.T) {
+		t.Parallel()
+		i := cmd().Invoke("required-flag", "--req-enum-array", "")
+		i.Environ.Set(serpent.CompletionModeEnv, "1")
+		io := fakeIO(i)
+		err := i.Run()
+		require.NoError(t, err)
+		require.Equal(t, "foo\nbar\nqux\n", io.Stdout.String())
+	})
+
+	t.Run("EnumArrayEqualsOK", func(t *testing.T) {
+		t.Parallel()
+		i := cmd().Invoke("required-flag", "--req-enum-array=")
+		i.Environ.Set(serpent.CompletionModeEnv, "1")
+		io := fakeIO(i)
+		err := i.Run()
+		require.NoError(t, err)
+		require.Equal(t, "--req-enum-array=foo\n--req-enum-array=bar\n--req-enum-array=qux\n", io.Stdout.String())
+	})
+
+	t.Run("EnumArrayEqualsBeginQuotesOK", func(t *testing.T) {
+		t.Parallel()
+		i := cmd().Invoke("required-flag", "--req-enum-array=\"")
+		i.Environ.Set(serpent.CompletionModeEnv, "1")
+		io := fakeIO(i)
+		err := i.Run()
+		require.NoError(t, err)
+		require.Equal(t, "--req-enum-array=foo\n--req-enum-array=bar\n--req-enum-array=qux\n", io.Stdout.String())
+	})
+
 }
 
 func TestFileCompletion(t *testing.T) {
@@ -201,3 +234,108 @@ func TestFileCompletion(t *testing.T) {
 		})
 	}
 }
+
+func TestCompletionInstall(t *testing.T) {
+	t.Parallel()
+
+	t.Run("InstallingNew", func(t *testing.T) {
+		dir := t.TempDir()
+		path := filepath.Join(dir, "fake.sh")
+		shell := &fakeShell{baseInstallDir: dir, programName: "fake"}
+
+		err := completion.InstallShellCompletion(shell)
+		require.NoError(t, err)
+		contents, err := os.ReadFile(path)
+		require.NoError(t, err)
+		require.Equal(t, "# ============ BEGIN fake COMPLETION ============\nFAKE_COMPLETION\n# ============ END fake COMPLETION ==============\n", string(contents))
+	})
+
+	cases := []struct {
+		name     string
+		input    []byte
+		expected []byte
+		errMsg   string
+	}{
+		{
+			name:     "InstallingAppend",
+			input:    []byte("FAKE_SCRIPT"),
+			expected: []byte("FAKE_SCRIPT\n# ============ BEGIN fake COMPLETION ============\nFAKE_COMPLETION\n# ============ END fake COMPLETION ==============\n"),
+		},
+		{
+			name:     "InstallReplaceBeginning",
+			input:    []byte("# ============ BEGIN fake COMPLETION ============\nOLD_COMPLETION\n# ============ END fake COMPLETION ==============\nFAKE_SCRIPT\n"),
+			expected: []byte("# ============ BEGIN fake COMPLETION ============\nFAKE_COMPLETION\n# ============ END fake COMPLETION ==============\nFAKE_SCRIPT\n"),
+		},
+		{
+			name:     "InstallReplaceMiddle",
+			input:    []byte("FAKE_SCRIPT\n# ============ BEGIN fake COMPLETION ============\nOLD_COMPLETION\n# ============ END fake COMPLETION ==============\nFAKE_SCRIPT\n"),
+			expected: []byte("FAKE_SCRIPT\n# ============ BEGIN fake COMPLETION ============\nFAKE_COMPLETION\n# ============ END fake COMPLETION ==============\nFAKE_SCRIPT\n"),
+		},
+		{
+			name:     "InstallReplaceEnd",
+			input:    []byte("FAKE_SCRIPT\n# ============ BEGIN fake COMPLETION ============\nOLD_COMPLETION\n# ============ END fake COMPLETION ==============\n"),
+			expected: []byte("FAKE_SCRIPT\n# ============ BEGIN fake COMPLETION ============\nFAKE_COMPLETION\n# ============ END fake COMPLETION ==============\n"),
+		},
+		{
+			name:   "InstallNoFooter",
+			input:  []byte("FAKE_SCRIPT\n# ============ BEGIN fake COMPLETION ============\nOLD_COMPLETION\n"),
+			errMsg: "missing completion footer",
+		},
+		{
+			name:   "InstallNoHeader",
+			input:  []byte("OLD_COMPLETION\n# ============ END fake COMPLETION ==============\n"),
+			errMsg: "missing completion header",
+		},
+		{
+			name:   "InstallBadOrder",
+			input:  []byte("# ============ END fake COMPLETION ==============\nFAKE_COMPLETION\n# ============ BEGIN fake COMPLETION =============="),
+			errMsg: "header after footer",
+		},
+	}
+
+	for _, tc := range cases {
+		tc := tc
+		t.Run(tc.name, func(t *testing.T) {
+			dir := t.TempDir()
+			path := filepath.Join(dir, "fake.sh")
+			err := os.WriteFile(path, tc.input, 0o644)
+			require.NoError(t, err)
+
+			shell := &fakeShell{baseInstallDir: dir, programName: "fake"}
+			err = completion.InstallShellCompletion(shell)
+			if tc.errMsg != "" {
+				require.ErrorContains(t, err, tc.errMsg)
+				return
+			} else {
+				require.NoError(t, err)
+				contents, err := os.ReadFile(path)
+				require.NoError(t, err)
+				require.Equal(t, tc.expected, contents)
+			}
+		})
+	}
+}
+
+type fakeShell struct {
+	baseInstallDir string
+	programName    string
+}
+
+func (f *fakeShell) ProgramName() string {
+	return f.programName
+}
+
+var _ completion.Shell = &fakeShell{}
+
+func (f *fakeShell) InstallPath() (string, error) {
+	return filepath.Join(f.baseInstallDir, "fake.sh"), nil
+}
+
+func (f *fakeShell) Name() string {
+	return "Fake"
+}
+
+func (f *fakeShell) WriteCompletion(w io.Writer) error {
+	_, err := w.Write([]byte("\nFAKE_COMPLETION\n"))
+	return err
+}
diff --git a/example/completetest/main.go b/example/completetest/main.go
index 920e705..add6d5c 100644
--- a/example/completetest/main.go
+++ b/example/completetest/main.go
@@ -1,6 +1,7 @@
 package main
 
 import (
+	"fmt"
 	"os"
 	"strings"
 
@@ -11,24 +12,21 @@ import (
 // installCommand returns a serpent command that helps
 // a user configure their shell to use serpent's completion.
 func installCommand() *serpent.Command {
-	defaultShell, err := completion.DetectUserShell()
-	if err != nil {
-		defaultShell = "bash"
-	}
-
 	var shell string
 	return &serpent.Command{
-		Use:   "completion",
+		Use:   "completion [--shell <shell>]",
 		Short: "Generate completion scripts for the given shell.",
 		Handler: func(inv *serpent.Invocation) error {
-			completion.WriteCompletion(inv.Stdout, shell, inv.Command.Parent.Name())
-			return nil
+			defaultShell, err := completion.DetectUserShell(inv.Command.Parent.Name())
+			if err != nil {
+				return fmt.Errorf("Could not detect user shell, please specify a shell using `--shell`")
+			}
+			return defaultShell.WriteCompletion(inv.Stdout)
 		},
 		Options: serpent.OptionSet{
 			{
 				Flag:          "shell",
 				FlagShorthand: "s",
-				Default:       defaultShell,
 				Description:   "The shell to generate a completion script for.",
 				Value:         completion.ShellOptions(&shell),
 			},
@@ -42,6 +40,7 @@ func main() {
 		upper    bool
 		fileType string
 		fileArr  []string
+		types    []string
 	)
 	cmd := serpent.Command{
 		Use:   "completetest <text>",
@@ -109,6 +108,11 @@ func main() {
 						Description: "Extra files.",
 						Value:       serpent.StringArrayOf(&fileArr),
 					},
+					{
+						Name:  "types",
+						Flag:  "types",
+						Value: serpent.EnumArrayOf(&types, "binary", "text"),
+					},
 				},
 				CompletionHandler: completion.FileHandler(nil),
 				Middleware:        serpent.RequireNArgs(1),
diff --git a/go.mod b/go.mod
index 8bd432e..1c2880c 100644
--- a/go.mod
+++ b/go.mod
@@ -6,8 +6,10 @@ require (
 	cdr.dev/slog v1.6.2-0.20240126064726-20367d4aede6
 	github.com/coder/pretty v0.0.0-20230908205945-e89ba86370e0
 	github.com/hashicorp/go-multierror v1.1.1
+	github.com/mitchellh/go-homedir v1.1.0
 	github.com/mitchellh/go-wordwrap v1.0.1
 	github.com/muesli/termenv v0.15.2
+	github.com/natefinch/atomic v1.0.1
 	github.com/pion/udp v0.1.4
 	github.com/spf13/pflag v1.0.5
 	github.com/stretchr/testify v1.8.4
diff --git a/go.sum b/go.sum
index 63d175d..a1106fc 100644
--- a/go.sum
+++ b/go.sum
@@ -46,12 +46,16 @@ github.com/mattn/go-isatty v0.0.20 h1:xfD0iDuEKnDkl03q4limB+vH+GxLEtL/jb4xVJSWWE
 github.com/mattn/go-isatty v0.0.20/go.mod h1:W+V8PltTTMOvKvAeJH7IuucS94S2C6jfK/D7dTCTo3Y=
 github.com/mattn/go-runewidth v0.0.15 h1:UNAjwbU9l54TA3KzvqLGxwWjHmMgBUVhBiTjelZgg3U=
 github.com/mattn/go-runewidth v0.0.15/go.mod h1:Jdepj2loyihRzMpdS35Xk/zdY8IAYHsh153qUoGf23w=
+github.com/mitchellh/go-homedir v1.1.0 h1:lukF9ziXFxDFPkA1vsr5zpc1XuPDn/wFntq5mG+4E0Y=
+github.com/mitchellh/go-homedir v1.1.0/go.mod h1:SfyaCUpYCn1Vlf4IUYiD9fPX4A5wJrkLzIz1N1q0pr0=
 github.com/mitchellh/go-wordwrap v1.0.1 h1:TLuKupo69TCn6TQSyGxwI1EblZZEsQ0vMlAFQflz0v0=
 github.com/mitchellh/go-wordwrap v1.0.1/go.mod h1:R62XHJLzvMFRBbcrT7m7WgmE1eOyTSsCt+hzestvNj0=
 github.com/muesli/reflow v0.3.0 h1:IFsN6K9NfGtjeggFP+68I4chLZV2yIKsXJFNZ+eWh6s=
 github.com/muesli/reflow v0.3.0/go.mod h1:pbwTDkVPibjO2kyvBQRBxTWEEGDGq0FlB1BIKtnHY/8=
 github.com/muesli/termenv v0.15.2 h1:GohcuySI0QmI3wN8Ok9PtKGkgkFIk7y6Vpb5PvrY+Wo=
 github.com/muesli/termenv v0.15.2/go.mod h1:Epx+iuz8sNs7mNKhxzH4fWXGNpZwUaJKRS1noLXviQ8=
+github.com/natefinch/atomic v1.0.1 h1:ZPYKxkqQOx3KZ+RsbnP/YsgvxWQPGxjC0oBt2AhwV0A=
+github.com/natefinch/atomic v1.0.1/go.mod h1:N/D/ELrljoqDyT3rZrsUmtsuzvHkeB/wWjHV22AZRbM=
 github.com/pion/logging v0.2.2/go.mod h1:k0/tDVsRCX2Mb2ZEmTqNa7CWsQPc+YYCB7Q+5pahoms=
 github.com/pion/transport/v2 v2.0.0 h1:bsMYyqHCbkvHwj+eNCFBuxtlKndKfyGI2vaQmM3fIE4=
 github.com/pion/transport/v2 v2.0.0/go.mod h1:HS2MEBJTwD+1ZI2eSXSvHJx/HnzQqRy2/LXxt6eVMHc=
diff --git a/help.go b/help.go
index 3dc49a4..533be11 100644
--- a/help.go
+++ b/help.go
@@ -95,6 +95,8 @@ var defaultHelpTemplate = func() *template.Template {
 					switch v := opt.Value.(type) {
 					case *Enum:
 						return strings.Join(v.Choices, "|")
+					case *EnumArray:
+						return fmt.Sprintf("[%s]", strings.Join(v.Choices, "|"))
 					default:
 						return v.Type()
 					}
diff --git a/option.go b/option.go
index fccc67e..2780fc6 100644
--- a/option.go
+++ b/option.go
@@ -352,7 +352,7 @@ func (optSet OptionSet) ByFlag(flag string) *Option {
 	}
 	for i := range optSet {
 		opt := &optSet[i]
-		if opt.Flag == flag || opt.FlagShorthand == flag {
+		if opt.Flag == flag {
 			return opt
 		}
 	}
diff --git a/values.go b/values.go
index 25fc20f..79c8e2c 100644
--- a/values.go
+++ b/values.go
@@ -191,7 +191,10 @@ func (String) Type() string {
 	return "string"
 }
 
-var _ pflag.SliceValue = &StringArray{}
+var (
+	_ pflag.SliceValue = &StringArray{}
+	_ pflag.Value      = &StringArray{}
+)
 
 // StringArray is a slice of strings that implements pflag.Value and pflag.SliceValue.
 type StringArray []string
@@ -527,7 +530,7 @@ func EnumOf(v *string, choices ...string) *Enum {
 
 func (e *Enum) Set(v string) error {
 	for _, c := range e.Choices {
-		if v == c {
+		if strings.EqualFold(v, c) {
 			*e.Value = v
 			return nil
 		}
@@ -628,3 +631,76 @@ func (p *YAMLConfigPath) String() string {
 func (*YAMLConfigPath) Type() string {
 	return "yaml-config-path"
 }
+
+var _ pflag.SliceValue = (*EnumArray)(nil)
+var _ pflag.Value = (*EnumArray)(nil)
+
+type EnumArray struct {
+	Choices []string
+	Value   *[]string
+}
+
+func (e *EnumArray) Append(s string) error {
+	for _, c := range e.Choices {
+		if strings.EqualFold(s, c) {
+			*e.Value = append(*e.Value, s)
+			return nil
+		}
+	}
+	return xerrors.Errorf("invalid choice: %s, should be one of %v", s, e.Choices)
+}
+
+func (e *EnumArray) GetSlice() []string {
+	return *e.Value
+}
+
+func (e *EnumArray) Replace(ss []string) error {
+	for _, s := range ss {
+		found := false
+		for _, c := range e.Choices {
+			if strings.EqualFold(s, c) {
+				found = true
+				break
+			}
+		}
+		if !found {
+			return xerrors.Errorf("invalid choice: %s, should be one of %v", s, e.Choices)
+		}
+	}
+	*e.Value = ss
+	return nil
+}
+
+func (e *EnumArray) Set(v string) error {
+	if v == "" {
+		*e.Value = nil
+		return nil
+	}
+	ss, err := readAsCSV(v)
+	if err != nil {
+		return err
+	}
+	for _, s := range ss {
+		err := e.Append(s)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func (e *EnumArray) String() string {
+	return writeAsCSV(*e.Value)
+}
+
+func (e *EnumArray) Type() string {
+	return fmt.Sprintf("enum-array[%v]", strings.Join(e.Choices, "\\|"))
+}
+
+func EnumArrayOf(v *[]string, choices ...string) *EnumArray {
+	choices = append([]string{}, choices...)
+	return &EnumArray{
+		Choices: choices,
+		Value:   v,
+	}
+}