diff --git a/libraries/AP_HAL_ChibiOS/hwdef/common/flash.c b/libraries/AP_HAL_ChibiOS/hwdef/common/flash.c
index 02852873e0..9595e5fafe 100644
--- a/libraries/AP_HAL_ChibiOS/hwdef/common/flash.c
+++ b/libraries/AP_HAL_ChibiOS/hwdef/common/flash.c
@@ -112,9 +112,12 @@ static const uint32_t flash_memmap[STM32_FLASH_NPAGES] = { KB(32), KB(32), KB(32
 #elif defined(STM32H7)
 #define STM32_FLASH_NPAGES  (BOARD_FLASH_SIZE / 128)
 #define STM32_FLASH_FIXED_PAGE_SIZE 128
-#elif defined(STM32F1)
+#elif defined(STM32F100_MCUCONF) || defined(STM32F103_MCUCONF)
 #define STM32_FLASH_NPAGES BOARD_FLASH_SIZE
 #define STM32_FLASH_FIXED_PAGE_SIZE 1
+#elif defined(STM32F105_MCUCONF)
+#define STM32_FLASH_NPAGES (BOARD_FLASH_SIZE/2)
+#define STM32_FLASH_FIXED_PAGE_SIZE 2
 #else
 #error "Unsupported processor for flash.c"
 #endif