diff --git a/arch/arm/boot/dts/am4372.dtsi b/arch/arm/boot/dts/am4372.dtsi
index 46660ff..4367f75 100644
--- a/arch/arm/boot/dts/am4372.dtsi
+++ b/arch/arm/boot/dts/am4372.dtsi
@@ -168,6 +168,7 @@
 			reg = <0x480C8000 0x200>;
 			interrupts = <GIC_SPI 77 IRQ_TYPE_LEVEL_HIGH>;
 			ti,hwmods = "mailbox";
+			#mbox-cells = <1>;
 			ti,mbox-num-users = <4>;
 			ti,mbox-num-fifos = <8>;
 			mbox_wkupm3: wkup_m3 {