diff --git a/fs/bcachefs/xattr_format.h b/fs/bcachefs/xattr_format.h
index e9f810539552..c7916011ef34 100644
--- a/fs/bcachefs/xattr_format.h
+++ b/fs/bcachefs/xattr_format.h
@@ -13,7 +13,7 @@ struct bch_xattr {
 	__u8			x_type;
 	__u8			x_name_len;
 	__le16			x_val_len;
-	__u8			x_name[];
+	__u8			x_name[] __counted_by(x_name_len);
 } __packed __aligned(8);
 
 #endif /* _BCACHEFS_XATTR_FORMAT_H */