diff --git a/libraries/AP_HAL_ChibiOS/hwdef/common/stm32_util.c b/libraries/AP_HAL_ChibiOS/hwdef/common/stm32_util.c
index b9a94d294c..35e01fd945 100644
--- a/libraries/AP_HAL_ChibiOS/hwdef/common/stm32_util.c
+++ b/libraries/AP_HAL_ChibiOS/hwdef/common/stm32_util.c
@@ -321,7 +321,7 @@ void peripheral_power_enable(void)
 #endif
 }
 
-#if defined(STM32F7) || defined(STM32H7) || defined(STM32F4)
+#if defined(STM32F7) || defined(STM32H7) || defined(STM32F4) || defined(STM32F3)
 /*
   read mode of a pin. This allows a pin config to be read, changed and
   then written back
diff --git a/libraries/AP_HAL_ChibiOS/hwdef/common/stm32_util.h b/libraries/AP_HAL_ChibiOS/hwdef/common/stm32_util.h
index 0681e6e917..ecd5c4a77b 100644
--- a/libraries/AP_HAL_ChibiOS/hwdef/common/stm32_util.h
+++ b/libraries/AP_HAL_ChibiOS/hwdef/common/stm32_util.h
@@ -78,7 +78,7 @@ void malloc_init(void);
   read mode of a pin. This allows a pin config to be read, changed and
   then written back
  */
-#if defined(STM32F7) || defined(STM32H7) || defined(STM32F4)
+#if defined(STM32F7) || defined(STM32H7) || defined(STM32F4) || defined(STM32F3)
 iomode_t palReadLineMode(ioline_t line);
 
 enum PalPushPull {