diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 1f1ea8529421f..0fe3ccec62a52 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -1312,7 +1312,8 @@ static int smack_inode_setxattr(struct mnt_idmap *idmap,
 		check_star = 1;
 	} else if (strcmp(name, XATTR_NAME_SMACKTRANSMUTE) == 0) {
 		check_priv = 1;
-		if (size != TRANS_TRUE_SIZE ||
+		if (!S_ISDIR(d_backing_inode(dentry)->i_mode) ||
+		    size != TRANS_TRUE_SIZE ||
 		    strncmp(value, TRANS_TRUE, TRANS_TRUE_SIZE) != 0)
 			rc = -EINVAL;
 	} else