diff --git a/arch/arm/boot/dts/stm32f746.dtsi b/arch/arm/boot/dts/stm32f746.dtsi
index 1479e3eb05fa455d88dbbbc2c25dc6cc1961ea10..f48d06a80d1d67e09cb2e0ba2a9873583df28947 100644
--- a/arch/arm/boot/dts/stm32f746.dtsi
+++ b/arch/arm/boot/dts/stm32f746.dtsi
@@ -297,7 +297,7 @@ rtc: rtc@40002800 {
 			interrupt-parent = <&exti>;
 			interrupts = <17 1>;
 			interrupt-names = "alarm";
-			st,syscfg = <&pwrcfg>;
+			st,syscfg = <&pwrcfg 0x00 0x100>;
 			status = "disabled";
 		};