diff --git a/arch/arm/boot/dts/r7s72100-rskrza1.dts b/arch/arm/boot/dts/r7s72100-rskrza1.dts
index 02b59c5b3c53..cab5857bfb41 100644
--- a/arch/arm/boot/dts/r7s72100-rskrza1.dts
+++ b/arch/arm/boot/dts/r7s72100-rskrza1.dts
@@ -43,6 +43,10 @@ &usb_x1_clk {
 	clock-frequency = <48000000>;
 };
 
+&rtc_x1_clk {
+	clock-frequency = <32768>;
+};
+
 &mtu2 {
 	status = "okay";
 };