diff --git a/arch/arm/boot/dts/stm32f746.dtsi b/arch/arm/boot/dts/stm32f746.dtsi
index 09d6649471b555ef30f976723c10bcc4715aa773..af4bfd4a40be6b96074e8829b1856b7ea512137d 100644
--- a/arch/arm/boot/dts/stm32f746.dtsi
+++ b/arch/arm/boot/dts/stm32f746.dtsi
@@ -320,6 +320,8 @@
 			reg = <0x40023800 0x400>;
 			clocks = <&clk_hse>, <&clk_i2s_ckin>;
 			st,syscfg = <&pwrcfg>;
+			assigned-clocks = <&rcc 1 CLK_HSE_RTC>;
+			assigned-clock-rates = <1000000>;
 		};
 	};
 };