diff --git a/firmware/config/boards/at_start_f435/board.mk b/firmware/config/boards/at_start_f435/board.mk
index 7c29a54071..338452bc3a 100644
--- a/firmware/config/boards/at_start_f435/board.mk
+++ b/firmware/config/boards/at_start_f435/board.mk
@@ -22,7 +22,7 @@ CONFDIR = $(PROJECT_DIR)/hw_layer/ports/at32/at32f4/cfg
 
 # This board uses ChibiOS MFS driver on internal flash
 DDEFS += -DHAL_USE_EFL=TRUE
-include $(PROJECT_DIR)/hw_layer/ports/stm32/calibrations_on_flash.mk
+include $(PROJECT_DIR)/hw_layer/ports/stm32/use_higher_level_flash_api.mk
 # This board has chip with dual-bank flash, bank 2 can be flashed in background
 DDEFS += -DEFI_FLASH_WRITE_THREAD=TRUE
 
diff --git a/firmware/config/boards/m74_9/board.mk b/firmware/config/boards/m74_9/board.mk
index f5fa3cb631..a483c77380 100644
--- a/firmware/config/boards/m74_9/board.mk
+++ b/firmware/config/boards/m74_9/board.mk
@@ -26,7 +26,7 @@ CONFDIR = $(PROJECT_DIR)/hw_layer/ports/at32/at32f4/cfg
 
 # This board uses ChibiOS MFS driver on internal flash
 DDEFS += -DHAL_USE_EFL=TRUE
-include $(PROJECT_DIR)/hw_layer/ports/stm32/calibrations_on_flash.mk
+include $(PROJECT_DIR)/hw_layer/ports/stm32/use_higher_level_flash_api.mk
 # This board has chip with dual-bank flash, bank 2 can be flashed in background
 DDEFS += -DEFI_FLASH_WRITE_THREAD=TRUE
 
diff --git a/firmware/config/boards/subaru_eg33/board.mk b/firmware/config/boards/subaru_eg33/board.mk
index 59b870c667..ccb75f633b 100644
--- a/firmware/config/boards/subaru_eg33/board.mk
+++ b/firmware/config/boards/subaru_eg33/board.mk
@@ -34,7 +34,7 @@ DDEFS += -DSNOR_SHARED_BUS=FALSE
 DDEFS += -DWSPI_USE_MUTUAL_EXCLUSION=FALSE
 
 # This board uses ChibiOS MFS driver on internal flash
-include $(PROJECT_DIR)/hw_layer/ports/stm32/calibrations_on_flash.mk
+include $(PROJECT_DIR)/hw_layer/ports/stm32/use_higher_level_flash_api.mk
 
 #Serial flash driver
 include $(PROJECT_DIR)/hw_layer/drivers/flash/sst26f_jedec.mk
diff --git a/firmware/config/stm32f4ems/efifeatures.h b/firmware/config/stm32f4ems/efifeatures.h
index c8488e67e6..7da4ea909b 100644
--- a/firmware/config/stm32f4ems/efifeatures.h
+++ b/firmware/config/stm32f4ems/efifeatures.h
@@ -174,10 +174,13 @@
 #define TRIGGER_EXTREME_LOGGING FALSE
 
 #ifndef EFI_STORAGE_INT_FLASH
+// historically we've started with low-level flash access with our own redundancy logic
+// todo: migrate to EFI_STORAGE_MFS which provides same functionality and more!
 #define EFI_STORAGE_INT_FLASH   TRUE
 #endif
 
 #ifndef EFI_STORAGE_MFS
+// todo: this higher level API should replace EFI_STORAGE_INT_FLASH legacy implementation
 #define EFI_STORAGE_MFS         FALSE
 #endif
 
diff --git a/firmware/hw_layer/ports/stm32/calibrations_on_flash.mk b/firmware/hw_layer/ports/stm32/calibrations_on_flash.mk
deleted file mode 100644
index 0a9d840e98..0000000000
--- a/firmware/hw_layer/ports/stm32/calibrations_on_flash.mk
+++ /dev/null
@@ -1,3 +0,0 @@
-# see also 'HAL_USE_EFL' in case of internal flash
-
-DDEFS += -DEFI_STORAGE_INT_FLASH=FALSE -DEFI_STORAGE_MFS=TRUE
diff --git a/firmware/hw_layer/ports/stm32/use_higher_level_flash_api.mk b/firmware/hw_layer/ports/stm32/use_higher_level_flash_api.mk
new file mode 100644
index 0000000000..08cb1413e6
--- /dev/null
+++ b/firmware/hw_layer/ports/stm32/use_higher_level_flash_api.mk
@@ -0,0 +1,7 @@
+# this header is relevant both for modern driver to access internal flash, and for external flash persistence
+# see also 'HAL_USE_EFL' in case of internal flash
+
+# do not use legacy implementation to persist calibrations
+DDEFS += -DEFI_STORAGE_INT_FLASH=FALSE
+# use higher level API instead
+DDEFS += -DEFI_STORAGE_MFS=TRUE