diff --git a/ports/stm32/flash.c b/ports/stm32/flash.c
index 7c7d2f7b6e..5f96696a9f 100644
--- a/ports/stm32/flash.c
+++ b/ports/stm32/flash.c
@@ -70,10 +70,15 @@ static const flash_layout_t flash_layout[] = {
     { 0x08020000, 0x20000, 3 },
 };
 #else
+// This is for dual-bank mode disabled
 static const flash_layout_t flash_layout[] = {
     { 0x08000000, 0x08000, 4 },
     { 0x08020000, 0x20000, 1 },
+    #if FLASH_SECTOR_TOTAL == 8
     { 0x08040000, 0x40000, 3 },
+    #else
+    { 0x08040000, 0x40000, 7 },
+    #endif
 };
 #endif
 
@@ -139,6 +144,13 @@ static uint32_t get_page(uint32_t addr) {
 
 #endif
 
+bool flash_is_valid_addr(uint32_t addr) {
+    uint8_t last = MP_ARRAY_SIZE(flash_layout) - 1;
+    uint32_t end_of_flash = flash_layout[last].base_address +
+        flash_layout[last].sector_count * flash_layout[last].sector_size;
+    return flash_layout[0].base_address <= addr && addr < end_of_flash;
+}
+
 uint32_t flash_get_sector_info(uint32_t addr, uint32_t *start_addr, uint32_t *size) {
     if (addr >= flash_layout[0].base_address) {
         uint32_t sector_index = 0;
diff --git a/ports/stm32/flash.h b/ports/stm32/flash.h
index 048914e501..12cdaca55a 100644
--- a/ports/stm32/flash.h
+++ b/ports/stm32/flash.h
@@ -26,6 +26,7 @@
 #ifndef MICROPY_INCLUDED_STM32_FLASH_H
 #define MICROPY_INCLUDED_STM32_FLASH_H
 
+bool flash_is_valid_addr(uint32_t addr);
 uint32_t flash_get_sector_info(uint32_t addr, uint32_t *start_addr, uint32_t *size);
 int flash_erase(uint32_t flash_dest, uint32_t num_word32);
 int flash_write(uint32_t flash_dest, const uint32_t *src, uint32_t num_word32);