diff --git a/cmd/interfacer/main.go b/cmd/interfacer/main.go
index 5f0b2f7..e8e714d 100644
--- a/cmd/interfacer/main.go
+++ b/cmd/interfacer/main.go
@@ -2,8 +2,11 @@
 package main
 
 import (
+	"bytes"
+	"errors"
 	"flag"
 	"fmt"
+	"go/format"
 	"os"
 	"strings"
 	"text/template"
@@ -40,31 +43,24 @@ type vars struct {
 	Interface     interfaces.Interface
 }
 
-func nonil(err ...error) error {
-	for _, e := range err {
-		if e != nil {
-			return e
-		}
+func main() {
+	if err := run(); err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
 	}
-	return nil
 }
 
-func die(v interface{}) {
-	fmt.Fprintln(os.Stderr, v)
-	os.Exit(1)
-}
-
-func main() {
+func run() error {
 	flag.Parse()
 	if *query == "" {
-		die("empty -for flag value; see -help for details")
+		return errors.New("empty -for flag value; see -help for details")
 	}
 	if *output == "" {
-		die("empty -o flag value; see -help for details")
+		return errors.New("empty -o flag value; see -help for details")
 	}
 	q, err := interfaces.ParseQuery(*query)
 	if err != nil {
-		die(err)
+		return err
 	}
 	opts := &interfaces.Options{
 		Query:      q,
@@ -72,7 +68,7 @@ func main() {
 	}
 	i, err := interfaces.NewWithOptions(opts)
 	if err != nil {
-		die(err)
+		return err
 	}
 	v := &vars{
 		Type:      fmt.Sprintf(`"%s"`, *query),
@@ -85,15 +81,24 @@ func main() {
 	} else {
 		v.InterfaceName = *as
 	}
+	var buf bytes.Buffer
+	if err := tmpl.Execute(&buf, v); err != nil {
+		return err
+	}
+	formatted, err := format.Source(buf.Bytes())
+	if err != nil {
+		return err
+	}
 	f := os.Stdout
 	if *output != "-" {
 		f, err = os.OpenFile(*output, os.O_TRUNC|os.O_CREATE|os.O_WRONLY, 0644)
 		if err != nil {
-			die(err)
+			return err
 		}
+		defer f.Close()
 	}
-	err = nonil(tmpl.Execute(f, v), f.Close())
-	if err != nil {
-		die(err)
+	if _, err := f.Write(formatted); err != nil {
+		return err
 	}
+	return nil
 }