diff --git a/arch/arm/boot/dts/r8a7790-lager.dts b/arch/arm/boot/dts/r8a7790-lager.dts
index 67a69399ba19..57569cba1528 100644
--- a/arch/arm/boot/dts/r8a7790-lager.dts
+++ b/arch/arm/boot/dts/r8a7790-lager.dts
@@ -58,6 +58,10 @@ fixedregulator3v3: fixedregulator@0 {
 	};
 };
 
+&extal_clk {
+	clock-frequency = <20000000>;
+};
+
 &pfc {
 	pinctrl-0 = <&scif0_pins &scif1_pins>;
 	pinctrl-names = "default";