diff --git a/fs/namespace.c b/fs/namespace.c
index 8634d56..5f75969 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -2815,7 +2815,7 @@ long do_mount(const char *dev_name, const char __user *dir_name,
 		mnt_flags |= MNT_NODIRATIME;
 	if (flags & MS_STRICTATIME)
 		mnt_flags &= ~(MNT_RELATIME | MNT_NOATIME);
-	if (flags & SB_RDONLY)
+	if (flags & MS_RDONLY)
 		mnt_flags |= MNT_READONLY;
 
 	/* The default atime for remount is preservation */