diff --git a/arch/sandbox/dts/test.dts b/arch/sandbox/dts/test.dts
index 8930009..686c215 100644
--- a/arch/sandbox/dts/test.dts
+++ b/arch/sandbox/dts/test.dts
@@ -216,6 +216,17 @@
 		};
 	};
 
+	mbox: mbox {
+		compatible = "sandbox,mbox";
+		#mbox-cells = <1>;
+	};
+
+	mbox-test {
+		compatible = "sandbox,mbox-test";
+		mboxes = <&mbox 100>, <&mbox 1>;
+		mbox-names = "other", "test";
+	};
+
 	mmc {
 		compatible = "sandbox,mmc";
 	};