1 files changed, 10 insertions, 2 deletions
diff --git a/src/io/fs/readdir_test.go b/src/io/fs/readdir_test.go
index 46a4bc2788..405bfa67ca 100644
--- a/src/io/fs/readdir_test.go
+++ b/src/io/fs/readdir_test.go
@@ -16,12 +16,12 @@ func (readDirOnly) Open(name string) (File, error) { return nil, ErrNotExist }
 func TestReadDir(t *testing.T) {
 	check := func(desc string, dirs []DirEntry, err error) {
 		t.Helper()
-		if err != nil || len(dirs) != 1 || dirs[0].Name() != "hello.txt" {
+		if err != nil || len(dirs) != 2 || dirs[0].Name() != "hello.txt" || dirs[1].Name() != "sub" {
 			var names []string
 			for _, d := range dirs {
 				names = append(names, d.Name())
 			}
-			t.Errorf("ReadDir(%s) = %v, %v, want %v, nil", desc, names, err, []string{"hello.txt"})
+			t.Errorf("ReadDir(%s) = %v, %v, want %v, nil", desc, names, err, []string{"hello.txt", "sub"})
 		}
 	}
 
@@ -32,4 +32,12 @@ func TestReadDir(t *testing.T) {
 	// Test that ReadDir uses Open when the method is not present.
 	dirs, err = ReadDir(openOnly{testFsys}, ".")
 	check("openOnly", dirs, err)
+
+	// Test that ReadDir on Sub of . works (sub_test checks non-trivial subs).
+	sub, err := Sub(testFsys, ".")
+	if err != nil {
+		t.Fatal(err)
+	}
+	dirs, err = ReadDir(sub, ".")
+	check("sub(.)", dirs, err)
 }