diff --git a/target/linux/ramips/dts/mt7621_dlink_dir-2640-a1.dts b/target/linux/ramips/dts/mt7621_dlink_dir-2640-a1.dts
index 323a790600..0c2d80954d 100644
--- a/target/linux/ramips/dts/mt7621_dlink_dir-2640-a1.dts
+++ b/target/linux/ramips/dts/mt7621_dlink_dir-2640-a1.dts
@@ -1,4 +1,5 @@
 // SPDX-License-Identifier: GPL-2.0-or-later OR MIT
+/dts-v1/;
 
 #include "mt7621_dlink_dir-xx60-a1.dtsi"