diff --git a/.github/workflows/mount-windows.yml b/.github/workflows/mount-windows.yml
index cd9db56854..f63b58f77f 100644
--- a/.github/workflows/mount-windows.yml
+++ b/.github/workflows/mount-windows.yml
@@ -127,7 +127,7 @@ jobs:
 
         Start-Mount 'seaweed-mount'
 
-        Invoke-Tests 'exercise' @('test','-v','-timeout','20m','./test/winfsp','-mountpoint=S:\')
+        Invoke-Tests 'exercise' @('test','-v','-timeout','20m','./test/winfsp','-mountpoint=S:\','-filer=127.0.0.1:8888')
         Invoke-Tests 'persist-write' @('test','-v','-timeout','15m','./test/winfsp','-run','TestPersistence','-mountpoint=S:\','-phase=write','-filer=127.0.0.1:8888')
 
         Stop-Mount
diff --git a/test/winfsp/unicode_dir_test.go b/test/winfsp/unicode_dir_test.go
new file mode 100644
index 0000000000..8b0fed4976
--- /dev/null
+++ b/test/winfsp/unicode_dir_test.go
@@ -0,0 +1,219 @@
+package winfsp
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"os"
+	"path"
+	"path/filepath"
+	"sort"
+	"strings"
+	"testing"
+	"time"
+)
+
+// The names come from a report of a folder tree showing up in the WinFsp
+// drive percent-encoded: 负极全景 as %E8%B4%9F%E6%9E%81%E5%85%A8%E6%99%AF. The
+// literal percent-encoded sibling pins the other direction: a name that
+// really contains percent signs must not be decoded on the way through.
+var unicodeDirs = []string{
+	"负极全景",
+	"负极全景/OK原图",
+	"负极全景/OK渲染图",
+	"%E8%B4%9F%E6%9E%81%E5%85%A8%E6%99%AF",
+}
+
+// filerPathOf maps a path under the mount to the filer path it is stored at,
+// assuming the mount root is the filer root, which is how the CI job mounts.
+func filerPathOf(t *testing.T, mountPath string) string {
+	t.Helper()
+	rel, err := filepath.Rel(*mountPoint, mountPath)
+	if err != nil {
+		t.Fatalf("relative path of %s under %s: %v", mountPath, *mountPoint, err)
+	}
+	return "/" + filepath.ToSlash(rel)
+}
+
+func filerURL(filerPath string) string {
+	return (&url.URL{Scheme: "http", Host: *filerAddr, Path: filerPath}).String()
+}
+
+// listFromFiler returns the child names the filer holds for a directory,
+// straight from its JSON listing, so a name the mount stored percent-encoded
+// shows up as such instead of being decoded on the way back.
+func listFromFiler(filerDir string) ([]string, error) {
+	req, err := http.NewRequest(http.MethodGet, filerURL(strings.TrimSuffix(filerDir, "/")+"/"), nil)
+	if err != nil {
+		return nil, err
+	}
+	req.Header.Set("Accept", "application/json")
+	resp, err := (&http.Client{Timeout: 30 * time.Second}).Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("GET %s: %s", req.URL, resp.Status)
+	}
+	var listing struct {
+		Entries []struct{ FullPath string }
+	}
+	if err := json.NewDecoder(resp.Body).Decode(&listing); err != nil {
+		return nil, fmt.Errorf("decode listing of %s: %v", filerDir, err)
+	}
+	names := make([]string, 0, len(listing.Entries))
+	for _, e := range listing.Entries {
+		names = append(names, path.Base(e.FullPath))
+	}
+	sort.Strings(names)
+	return names, nil
+}
+
+func filerRequest(method, filerPath string, body []byte) error {
+	req, err := http.NewRequest(method, filerURL(filerPath), bytes.NewReader(body))
+	if err != nil {
+		return err
+	}
+	if body != nil {
+		req.Header.Set("Content-Type", "application/octet-stream")
+	}
+	resp, err := (&http.Client{Timeout: 30 * time.Second}).Do(req)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode/100 != 2 {
+		msg, _ := io.ReadAll(resp.Body)
+		return fmt.Errorf("%s %s: %s %s", method, req.URL, resp.Status, msg)
+	}
+	return nil
+}
+
+// mkdirOnFiler is the filer's own mkdir: a POST to a trailing-slash path with
+// no content type.
+func mkdirOnFiler(filerDir string) error {
+	return filerRequest(http.MethodPost, strings.TrimSuffix(filerDir, "/")+"/", nil)
+}
+
+func mountNames(t *testing.T, dir string) []string {
+	t.Helper()
+	entries, err := os.ReadDir(dir)
+	if err != nil {
+		t.Fatalf("readdir %s: %v", dir, err)
+	}
+	names := make([]string, 0, len(entries))
+	for _, e := range entries {
+		names = append(names, e.Name())
+	}
+	sort.Strings(names)
+	return names
+}
+
+func expectNames(t *testing.T, where string, got, want []string) {
+	t.Helper()
+	sort.Strings(want)
+	if strings.Join(got, "\n") != strings.Join(want, "\n") {
+		t.Errorf("%s lists %q, want %q", where, got, want)
+	}
+}
+
+// TestUnicodeDirectoryTree builds the reported folder tree through the mount
+// and checks the names at every level, first as the mount lists them back and
+// then as the filer stored them.
+func TestUnicodeDirectoryTree(t *testing.T) {
+	dir := testRoot(t)
+	for _, rel := range unicodeDirs {
+		if err := os.Mkdir(filepath.Join(dir, filepath.FromSlash(rel)), 0755); err != nil {
+			t.Fatalf("mkdir %s: %v", rel, err)
+		}
+	}
+	leafFile := filepath.Join(dir, "负极全景", "OK原图", "图片.jpg")
+	if err := os.WriteFile(leafFile, []byte("图片"), 0644); err != nil {
+		t.Fatalf("write %s: %v", leafFile, err)
+	}
+
+	// Lookups by path are what Explorer does when it opens a folder, and go
+	// through a different route than listing.
+	for _, rel := range unicodeDirs {
+		info, err := os.Stat(filepath.Join(dir, filepath.FromSlash(rel)))
+		if err != nil {
+			t.Errorf("stat %s: %v", rel, err)
+		} else if !info.IsDir() {
+			t.Errorf("%s is not a directory", rel)
+		}
+	}
+	expectNames(t, "mount root", mountNames(t, dir), []string{"负极全景", "%E8%B4%9F%E6%9E%81%E5%85%A8%E6%99%AF"})
+	expectNames(t, "mount 负极全景", mountNames(t, filepath.Join(dir, "负极全景")), []string{"OK原图", "OK渲染图"})
+	expectNames(t, "mount 负极全景/OK原图", mountNames(t, filepath.Join(dir, "负极全景", "OK原图")), []string{"图片.jpg"})
+	if got, err := os.ReadFile(leafFile); err != nil {
+		t.Errorf("read %s: %v", leafFile, err)
+	} else if string(got) != "图片" {
+		t.Errorf("read %s: %q", leafFile, got)
+	}
+
+	if err := os.Rename(filepath.Join(dir, "负极全景", "OK渲染图"), filepath.Join(dir, "负极全景", "OK渲染图-改")); err != nil {
+		t.Fatalf("rename: %v", err)
+	}
+	expectNames(t, "mount 负极全景 after rename", mountNames(t, filepath.Join(dir, "负极全景")), []string{"OK原图", "OK渲染图-改"})
+
+	if *filerAddr == "" {
+		t.Log("no -filer given; skipping the check of what the filer stored")
+		return
+	}
+	root := filerPathOf(t, dir)
+	for _, check := range []struct {
+		dir  string
+		want []string
+	}{
+		{root, []string{"负极全景", "%E8%B4%9F%E6%9E%81%E5%85%A8%E6%99%AF"}},
+		{root + "/负极全景", []string{"OK原图", "OK渲染图-改"}},
+		{root + "/负极全景/OK原图", []string{"图片.jpg"}},
+	} {
+		got, err := listFromFiler(check.dir)
+		if err != nil {
+			t.Errorf("filer listing: %v", err)
+			continue
+		}
+		expectNames(t, "filer "+check.dir, got, check.want)
+	}
+}
+
+// TestUnicodeNamesCreatedOnFiler is the other direction: the tree is created
+// through the filer's HTTP API, in a directory the mount has not listed yet,
+// so the mount's first look at it has to fetch the names from the filer.
+func TestUnicodeNamesCreatedOnFiler(t *testing.T) {
+	if *filerAddr == "" {
+		t.Skip("no -filer given; this test creates entries through the filer")
+	}
+	dir := testRoot(t)
+	root := filerPathOf(t, dir)
+	for _, rel := range unicodeDirs {
+		if err := mkdirOnFiler(root + "/" + rel); err != nil {
+			t.Fatalf("filer mkdir %s: %v", rel, err)
+		}
+	}
+	if err := filerRequest(http.MethodPut, root+"/负极全景/OK原图/图片.jpg", []byte("图片")); err != nil {
+		t.Fatalf("filer put: %v", err)
+	}
+
+	expectNames(t, "mount root", mountNames(t, dir), []string{"负极全景", "%E8%B4%9F%E6%9E%81%E5%85%A8%E6%99%AF"})
+	expectNames(t, "mount 负极全景", mountNames(t, filepath.Join(dir, "负极全景")), []string{"OK原图", "OK渲染图"})
+	expectNames(t, "mount 负极全景/OK原图", mountNames(t, filepath.Join(dir, "负极全景", "OK原图")), []string{"图片.jpg"})
+	for _, rel := range unicodeDirs {
+		if info, err := os.Stat(filepath.Join(dir, filepath.FromSlash(rel))); err != nil {
+			t.Errorf("stat %s: %v", rel, err)
+		} else if !info.IsDir() {
+			t.Errorf("%s is not a directory", rel)
+		}
+	}
+	leafFile := filepath.Join(dir, "负极全景", "OK原图", "图片.jpg")
+	if got, err := os.ReadFile(leafFile); err != nil {
+		t.Errorf("read %s: %v", leafFile, err)
+	} else if string(got) != "图片" {
+		t.Errorf("read %s: %q", leafFile, got)
+	}
+}