diff --git a/src/os/dir_unix.go b/src/os/dir_unix.go
index eadc1660c2..6a0135b70b 100644
--- a/src/os/dir_unix.go
+++ b/src/os/dir_unix.go
@@ -46,11 +46,19 @@ func (d *dirInfo) close() {
 
 func (f *File) readdir(n int, mode readdirMode) (names []string, dirents []DirEntry, infos []FileInfo, err error) {
 	// If this file has no dirInfo, create one.
-	d := f.dirinfo.Load()
-	if d == nil {
-		d = new(dirInfo)
-		f.dirinfo.Store(d)
+	var d *dirInfo
+	for {
+		d = f.dirinfo.Load()
+		if d != nil {
+			break
+		}
+		newD := new(dirInfo)
+		if f.dirinfo.CompareAndSwap(nil, newD) {
+			d = newD
+			break
+		}
 	}
+
 	d.mu.Lock()
 	defer d.mu.Unlock()
 	if d.buf == nil {