diff --git a/arch/arm/boot/dts/r8a7778-bockw.dts b/arch/arm/boot/dts/r8a7778-bockw.dts
index 274a1b6fe329..00119754f7f0 100644
--- a/arch/arm/boot/dts/r8a7778-bockw.dts
+++ b/arch/arm/boot/dts/r8a7778-bockw.dts
@@ -61,6 +61,10 @@ ethernet@18300000 {
 	};
 };
 
+&extal_clk {
+	clock-frequency = <33333333>;
+};
+
 &mmcif {
 	pinctrl-0 = <&mmc_pins>;
 	pinctrl-names = "default";