diff --git a/cmd/minify/main.go b/cmd/minify/main.go
index 9e7641a05c..aeebc36093 100644
--- a/cmd/minify/main.go
+++ b/cmd/minify/main.go
@@ -4,6 +4,7 @@ import (
 	"bufio"
 	"fmt"
 	"io"
+	"io/fs"
 	"io/ioutil"
 	"log"
 	"net/url"
@@ -473,7 +474,7 @@ func sanitizePath(p string) string {
 	}
 	if isDir {
 		p += "/"
-	} else if info, err := os.Lstat(p); err == nil && info.Mode().IsDir() && info.Mode()&os.ModeSymlink == 0 {
+	} else if info, err := os.Lstat(p); err == nil && info.Mode().IsDir() && info.Mode()&fs.ModeSymlink == 0 {
 		p += "/"
 	}
 	if isCur {
@@ -499,11 +500,23 @@ func fileMatches(filename string) bool {
 	return true
 }
 
+type DirEntry struct {
+	fs.FileInfo
+}
+
+func (d DirEntry) Type() fs.FileMode {
+	return d.Mode().Type()
+}
+
+func (d DirEntry) Info() (fs.FileInfo, error) {
+	return d.FileInfo, nil
+}
+
 func createTasks(inputs []string, output string) ([]Task, []string, error) {
 	tasks := []Task{}
 	roots := []string{}
 	for _, input := range inputs {
-		var info os.FileInfo
+		var info fs.FileInfo
 		var err error
 		if !preserveSymlinks {
 			info, err = os.Stat(input)
@@ -514,7 +527,7 @@ func createTasks(inputs []string, output string) ([]Task, []string, error) {
 			return nil, nil, err
 		}
 
-		if info.Mode()&os.ModeSymlink != 0 {
+		if info.Mode()&fs.ModeSymlink != 0 {
 			if !sync {
 				Warning.Println("--sync not specified, omitting symbolic link", input)
 				continue
@@ -540,33 +553,33 @@ func createTasks(inputs []string, output string) ([]Task, []string, error) {
 			}
 			roots = append(roots, input)
 
-			var walkFn func(string, os.DirEntry, error) error
-			walkFn = func(path string, d os.DirEntry, err error) error {
+			var walkFn func(string, fs.DirEntry, error) error
+			walkFn = func(path string, d fs.DirEntry, err error) error {
 				if err != nil {
 					return err
 				} else if d.Name() == "." || d.Name() == ".." {
 					return nil
 				} else if len(d.Name()) == 0 || !hidden && d.Name()[0] == '.' {
 					if d.IsDir() {
-						return filepath.SkipDir
+						return fs.SkipDir
 					}
 					return nil
 				}
 				path = sanitizePath(path)
 
-				if !preserveSymlinks && d.Type()&os.ModeSymlink != 0 {
+				if !preserveSymlinks && d.Type()&fs.ModeSymlink != 0 {
 					// follow and dereference symlinks
 					info, err := os.Stat(path)
 					if err != nil {
 						return err
 					}
 					if info.IsDir() {
-						return WalkDir(input, path, walkFn)
+						return fs.WalkDir(os.DirFS(input), path, walkFn)
 					}
-					d = &statDirEntry{info}
+					d = DirEntry{info}
 				}
 
-				if preserveSymlinks && d.Type()&os.ModeSymlink != 0 {
+				if preserveSymlinks && d.Type()&fs.ModeSymlink != 0 {
 					// copy symlinks as is
 					if !sync {
 						Warning.Println("--sync not specified, omitting symbolic link", path)
@@ -589,7 +602,7 @@ func createTasks(inputs []string, output string) ([]Task, []string, error) {
 				}
 				return nil
 			}
-			if err := WalkDir(".", input, walkFn); err != nil {
+			if err := fs.WalkDir(os.DirFS("."), input, walkFn); err != nil {
 				return nil, nil, err
 			}
 		} else {
@@ -656,7 +669,7 @@ func minify(t Task) bool {
 	if t.sync {
 		if t.srcs[0] == t.dst {
 			return true
-		} else if info, err := os.Lstat(t.srcs[0]); preserveSymlinks && err == nil && info.Mode()&os.ModeSymlink != 0 {
+		} else if info, err := os.Lstat(t.srcs[0]); preserveSymlinks && err == nil && info.Mode()&fs.ModeSymlink != 0 {
 			src, err := os.Readlink(t.srcs[0])
 			if err != nil {
 				Error.Println(err)
diff --git a/cmd/minify/walkdir.go b/cmd/minify/walkdir.go
deleted file mode 100644
index 5cdc5eec41..0000000000
--- a/cmd/minify/walkdir.go
+++ /dev/null
@@ -1,119 +0,0 @@
-package main
-
-import (
-	"os"
-	"path"
-	"path/filepath"
-)
-
-// WalkDirFunc is the type of the function called by WalkDir to visit
-// each file or directory.
-//
-// The path argument contains the argument to WalkDir as a prefix.
-// That is, if WalkDir is called with root argument "dir" and finds a file
-// named "a" in that directory, the walk function will be called with
-// argument "dir/a".
-//
-// The d argument is the fs.DirEntry for the named path.
-//
-// The error result returned by the function controls how WalkDir
-// continues. If the function returns the special value SkipDir, WalkDir
-// skips the current directory (path if d.IsDir() is true, otherwise
-// path's parent directory). Otherwise, if the function returns a non-nil
-// error, WalkDir stops entirely and returns that error.
-//
-// The err argument reports an error related to path, signaling that
-// WalkDir will not walk into that directory. The function can decide how
-// to handle that error; as described earlier, returning the error will
-// cause WalkDir to stop walking the entire tree.
-//
-// WalkDir calls the function with a non-nil err argument in two cases.
-//
-// First, if the initial fs.Stat on the root directory fails, WalkDir
-// calls the function with path set to root, d set to nil, and err set to
-// the error from fs.Stat.
-//
-// Second, if a directory's ReadDir method fails, WalkDir calls the
-// function with path set to the directory's path, d set to an
-// fs.DirEntry describing the directory, and err set to the error from
-// ReadDir. In this second case, the function is called twice with the
-// path of the directory: the first call is before the directory read is
-// attempted and has err set to nil, giving the function a chance to
-// return SkipDir and avoid the ReadDir entirely. The second call is
-// after a failed ReadDir and reports the error from ReadDir.
-// (If ReadDir succeeds, there is no second call.)
-//
-// The differences between WalkDirFunc compared to filepath.WalkFunc are:
-//
-//   - The second argument has type fs.DirEntry instead of fs.FileInfo.
-//   - The function is called before reading a directory, to allow SkipDir
-//     to bypass the directory read entirely.
-//   - If a directory read fails, the function is called a second time
-//     for that directory to report the error.
-//
-type WalkDirFunc func(path string, d os.DirEntry, err error) error
-
-// walkDir recursively descends path, calling walkDirFn.
-func walkDir(fsys string, name string, d os.DirEntry, walkDirFn WalkDirFunc) error {
-	if err := walkDirFn(name, d, nil); err != nil || !d.IsDir() {
-		if err == filepath.SkipDir && d.IsDir() {
-			// Successfully skipped directory.
-			err = nil
-		}
-		return err
-	}
-
-	dirs, err := os.ReadDir(filepath.Join(fsys, name))
-	if err != nil {
-		// Second call, to report ReadDir error.
-		err = walkDirFn(name, d, err)
-		if err != nil {
-			return err
-		}
-	}
-
-	for _, d1 := range dirs {
-		name1 := path.Join(name, d1.Name())
-		if err := walkDir(fsys, name1, d1, walkDirFn); err != nil {
-			if err == filepath.SkipDir {
-				break
-			}
-			return err
-		}
-	}
-	return nil
-}
-
-// WalkDir walks the file tree rooted at root, calling fn for each file or
-// directory in the tree, including root.
-//
-// All errors that arise visiting files and directories are filtered by fn:
-// see the fs.WalkDirFunc documentation for details.
-//
-// The files are walked in lexical order, which makes the output deterministic
-// but requires WalkDir to read an entire directory into memory before proceeding
-// to walk that directory.
-//
-// WalkDir does not follow symbolic links found in directories,
-// but if root itself is a symbolic link, its target will be walked.
-func WalkDir(fsys string, root string, fn WalkDirFunc) error {
-	info, err := os.Stat(filepath.Join(fsys, root))
-	if err != nil {
-		err = fn(root, nil, err)
-	} else {
-		err = walkDir(fsys, root, &statDirEntry{info}, fn)
-	}
-	if err == filepath.SkipDir {
-		return nil
-	}
-	return err
-}
-
-type statDirEntry struct {
-	info os.FileInfo
-}
-
-func (d *statDirEntry) Name() string               { return d.info.Name() }
-func (d *statDirEntry) IsDir() bool                { return d.info.IsDir() }
-func (d *statDirEntry) Type() os.FileMode          { return d.info.Mode().Type() }
-func (d *statDirEntry) Info() (os.FileInfo, error) { return d.info, nil }
diff --git a/go.mod b/go.mod
index 73f66006cf..1757659f38 100644
--- a/go.mod
+++ b/go.mod
@@ -1,6 +1,6 @@
 module github.com/tdewolff/minify/v2
 
-go 1.13
+go 1.16
 
 require (
 	github.com/cheekybits/is v0.0.0-20150225183255-68e9c0620927 // indirect