diff --git a/flag-gen/assets_generate.go b/flag-gen/assets_generate.go
index b587253..c3847d6 100644
--- a/flag-gen/assets_generate.go
+++ b/flag-gen/assets_generate.go
@@ -7,45 +7,15 @@ import (
 	"github.com/shurcooL/vfsgen"
 	"log"
 	"net/http"
-	"os"
-	"time"
 )
 
-// zeroModTimeFileSystem is an http.FileSystem wrapper.
-// It exposes a filesystem exactly like Source, except
-// all file modification times are changed to zero.
-// See https://github.com/shurcooL/vfsgen/pull/40#issuecomment-355416103
-type zeroModTimeFileSystem struct {
-	Source http.FileSystem
-}
-
-func (fs zeroModTimeFileSystem) Open(name string) (http.File, error) {
-	f, err := fs.Source.Open(name)
-	return file{f}, err
-}
-
-type file struct {
-	http.File
-}
-
-func (f file) Stat() (os.FileInfo, error) {
-	fi, err := f.File.Stat()
-	return fileInfo{fi}, err
-}
-
-type fileInfo struct {
-	os.FileInfo
-}
-
-func (fi fileInfo) ModTime() time.Time { return time.Time{} }
-
 func main() {
-	err := vfsgen.Generate(zeroModTimeFileSystem{
-		Source: union.New(map[string]http.FileSystem{
-			"/templates": http.Dir("templates"),
-			"/source":    http.Dir("source"),
-		}),
-	}, vfsgen.Options{})
+	fs := union.New(map[string]http.FileSystem{
+		"/templates": http.Dir("templates"),
+		"/source":    http.Dir("source"),
+	})
+
+	err := vfsgen.Generate(fs, vfsgen.Options{})
 
 	if err != nil {
 		log.Fatal(err)