diff --git a/libraries/AP_HAL_ChibiOS/Flash.h b/libraries/AP_HAL_ChibiOS/Flash.h
new file mode 100644
index 0000000000..0101b7adb0
--- /dev/null
+++ b/libraries/AP_HAL_ChibiOS/Flash.h
@@ -0,0 +1,24 @@
+#pragma once
+
+#include <AP_HAL/AP_HAL.h>
+#include "AP_HAL_ChibiOS_Namespace.h"
+#include <AP_Common/Semaphore.h>
+#include "hwdef/common/flash.h"
+
+class ChibiOS::Flash : public AP_HAL::Flash {
+public:
+    uint32_t getpageaddr(uint32_t page) override { return stm32_flash_getpageaddr(page); }
+    uint32_t getpagesize(uint32_t page) override { return stm32_flash_getpagesize(page); }
+    uint32_t getnumpages(void) override { return stm32_flash_getnumpages(); }
+    bool erasepage(uint32_t page) override {
+        WITH_SEMAPHORE(sem);
+        return stm32_flash_erasepage(page); }
+    bool write(uint32_t addr, const void *buf, uint32_t count) override {
+        WITH_SEMAPHORE(sem);
+        return stm32_flash_write(addr, buf, count); }
+    void keep_unlocked(bool set) override { stm32_flash_keep_unlocked(set); }
+    bool ispageerased(uint32_t page) override { return stm32_flash_ispageerased(page); }
+
+private:
+    HAL_Semaphore sem;
+};
diff --git a/libraries/AP_HAL_ChibiOS/Storage.cpp b/libraries/AP_HAL_ChibiOS/Storage.cpp
index 45666cf78f..cbe987c480 100644
--- a/libraries/AP_HAL_ChibiOS/Storage.cpp
+++ b/libraries/AP_HAL_ChibiOS/Storage.cpp
@@ -251,9 +251,9 @@ void Storage::_flash_write(uint16_t line)
 bool Storage::_flash_write_data(uint8_t sector, uint32_t offset, const uint8_t *data, uint16_t length)
 {
 #ifdef STORAGE_FLASH_PAGE
-    size_t base_address = stm32_flash_getpageaddr(_flash_page+sector);
+    size_t base_address = hal.flash->getpageaddr(_flash_page+sector);
     for (uint8_t i=0; i<STORAGE_FLASH_RETRIES; i++) {
-        if (stm32_flash_write(base_address+offset, data, length)) {
+        if (hal.flash->write(base_address+offset, data, length)) {
             return true;
         }
         hal.scheduler->delay(1);
@@ -280,7 +280,7 @@ bool Storage::_flash_write_data(uint8_t sector, uint32_t offset, const uint8_t *
  */
 bool Storage::_flash_read_data(uint8_t sector, uint32_t offset, uint8_t *data, uint16_t length)
 {
-    size_t base_address = stm32_flash_getpageaddr(_flash_page+sector);
+    size_t base_address = hal.flash->getpageaddr(_flash_page+sector);
     const uint8_t *b = ((const uint8_t *)base_address)+offset;
     memcpy(data, b, length);
     return true;
@@ -292,7 +292,7 @@ bool Storage::_flash_read_data(uint8_t sector, uint32_t offset, uint8_t *data, u
 bool Storage::_flash_erase_sector(uint8_t sector)
 {
     for (uint8_t i=0; i<STORAGE_FLASH_RETRIES; i++) {
-        if (stm32_flash_erasepage(_flash_page+sector)) {
+        if (hal.flash->erasepage(_flash_page+sector)) {
             return true;
         }
         hal.scheduler->delay(1);
diff --git a/libraries/AP_HAL_ChibiOS/Storage.h b/libraries/AP_HAL_ChibiOS/Storage.h
index be9797c035..aeb0a6ec48 100644
--- a/libraries/AP_HAL_ChibiOS/Storage.h
+++ b/libraries/AP_HAL_ChibiOS/Storage.h
@@ -63,7 +63,7 @@ private:
 
 #ifdef STORAGE_FLASH_PAGE
     AP_FlashStorage _flash{_buffer,
-            stm32_flash_getpagesize(STORAGE_FLASH_PAGE),
+            hal.flash->getpagesize(STORAGE_FLASH_PAGE),
             FUNCTOR_BIND_MEMBER(&Storage::_flash_write_data, bool, uint8_t, uint32_t, const uint8_t *, uint16_t),
             FUNCTOR_BIND_MEMBER(&Storage::_flash_read_data, bool, uint8_t, uint32_t, uint8_t *, uint16_t),
             FUNCTOR_BIND_MEMBER(&Storage::_flash_erase_sector, bool, uint8_t),
diff --git a/libraries/AP_HAL_ChibiOS/Util.cpp b/libraries/AP_HAL_ChibiOS/Util.cpp
index ece3309a2d..06db0a2f94 100644
--- a/libraries/AP_HAL_ChibiOS/Util.cpp
+++ b/libraries/AP_HAL_ChibiOS/Util.cpp
@@ -235,7 +235,7 @@ bool Util::flash_bootloader()
         return false;
     }
 
-    const uint32_t addr = stm32_flash_getpageaddr(0);
+    const uint32_t addr = hal.flash->getpageaddr(0);
     if (!memcmp(fw, (const void*)addr, fw_size)) {
         hal.console->printf("Bootloader up-to-date\n");
         free(fw);
@@ -243,7 +243,7 @@ bool Util::flash_bootloader()
     }
 
     hal.console->printf("Erasing\n");
-    if (!stm32_flash_erasepage(0)) {
+    if (!hal.flash->erasepage(0)) {
         hal.console->printf("Erase failed\n");
         free(fw);
         return false;
@@ -252,7 +252,7 @@ bool Util::flash_bootloader()
     const uint8_t max_attempts = 10;
     for (uint8_t i=0; i<max_attempts; i++) {
         void *context = hal.scheduler->disable_interrupts_save();
-        bool ok = stm32_flash_write(addr, fw, fw_size);
+        bool ok = hal.flash->write(addr, fw, fw_size);
         hal.scheduler->restore_interrupts(context);
         if (!ok) {
             hal.console->printf("Flash failed! (attempt=%u/%u)\n",