diff --git a/arch/arm/boot/dts/r8a7791-henninger.dts b/arch/arm/boot/dts/r8a7791-henninger.dts
index 6e67cea3104cdf5001da5cbd2b0a460b5ed9e28c..0a655231d53148299d46dca8c477413fc798a097 100644
--- a/arch/arm/boot/dts/r8a7791-henninger.dts
+++ b/arch/arm/boot/dts/r8a7791-henninger.dts
@@ -35,6 +35,10 @@
 	};
 };
 
+&extal_clk {
+	clock-frequency = <20000000>;
+};
+
 &pfc {
 	scif0_pins: serial0 {
 		renesas,groups = "scif0_data_d";