diff --git a/arch/arm/src/stm32f7/stm32f76xx77xx_rcc.c b/arch/arm/src/stm32f7/stm32f76xx77xx_rcc.c
index 09167863db..0d784ff123 100644
--- a/arch/arm/src/stm32f7/stm32f76xx77xx_rcc.c
+++ b/arch/arm/src/stm32f7/stm32f76xx77xx_rcc.c
@@ -60,6 +60,15 @@
 
 #define HSE_DIVISOR (STM32_HSE_FREQUENCY + 500000) / 1000000
 
+/* If CONFIG_STM32F7_DSIHOST is defined in the board configuration, then
+ * STM32_RCC_DCKCFGR2_DSISRC must also be defined to selected the clock
+ * source.
+ */
+
+#ifndef STM32_RCC_DCKCFGR2_DSISRC
+#  define STM32_RCC_DCKCFGR2_DSISRC RCC_DCKCFGR2_DSISEL_PHY
+#endif
+
 /* FLASH wait states */
 
 #if !defined(BOARD_FLASH_WAITSTATES)