diff --git a/target/linux/ath79/dts/qca9558_mikrotik_routerboard-92x.dtsi b/target/linux/ath79/dts/qca9558_mikrotik_routerboard-92x.dtsi
index c48f997e89..85dd65f7a4 100644
--- a/target/linux/ath79/dts/qca9558_mikrotik_routerboard-92x.dtsi
+++ b/target/linux/ath79/dts/qca9558_mikrotik_routerboard-92x.dtsi
@@ -88,6 +88,7 @@
 			};
 
 			bios {
+				size = <0x1000>;
 				read-only;
 			};