diff --git a/vfs/vfsflags/vfsflags_unix.go b/vfs/vfsflags/vfsflags_unix.go
index 36fe6335d..f548c50e7 100644
--- a/vfs/vfsflags/vfsflags_unix.go
+++ b/vfs/vfsflags/vfsflags_unix.go
@@ -10,11 +10,11 @@ import (
 
 // add any extra platform specific flags
 func platformFlags(flagSet *pflag.FlagSet) {
-	flags.IntVarP(flagSet, &Opt.Umask, "umask", "", Opt.Umask, "Override the permission bits set by the filesystem.")
+	flags.IntVarP(flagSet, &Opt.Umask, "umask", "", Opt.Umask, "Override the permission bits set by the filesystem. Not supported on Windows.")
 	Opt.Umask = unix.Umask(0) // read the umask
 	unix.Umask(Opt.Umask)     // set it back to what it was
 	Opt.UID = uint32(unix.Geteuid())
 	Opt.GID = uint32(unix.Getegid())
-	flags.Uint32VarP(flagSet, &Opt.UID, "uid", "", Opt.UID, "Override the uid field set by the filesystem.")
-	flags.Uint32VarP(flagSet, &Opt.GID, "gid", "", Opt.GID, "Override the gid field set by the filesystem.")
+	flags.Uint32VarP(flagSet, &Opt.UID, "uid", "", Opt.UID, "Override the uid field set by the filesystem. Not supported on Windows.")
+	flags.Uint32VarP(flagSet, &Opt.GID, "gid", "", Opt.GID, "Override the gid field set by the filesystem. Not supported on Windows.")
 }