diff --git a/webdav/file.go b/webdav/file.go
index 9f53778..3fcc053 100644
--- a/webdav/file.go
+++ b/webdav/file.go
@@ -12,6 +12,7 @@
 	"os"
 	"path"
 	"path/filepath"
+	"runtime"
 	"strings"
 	"sync"
 	"time"
@@ -272,8 +273,14 @@
 	var n *memFSNode
 	if dir == nil {
 		// We're opening the root.
-		if flag&(os.O_WRONLY|os.O_RDWR) != 0 {
-			return nil, os.ErrPermission
+		if runtime.GOOS == "zos" {
+			if flag&os.O_WRONLY != 0 {
+				return nil, os.ErrPermission
+			}
+		} else {
+			if flag&(os.O_WRONLY|os.O_RDWR) != 0 {
+				return nil, os.ErrPermission
+			}
 		}
 		n, frag = &fs.root, "/"