-BOOT_START_OFFSET = 0x$(shell echo "obase=16; ($(FLASH_SIZE_KB) - $(BOOT_SECTION_SIZE_KB)) * 1024" | bc)
-BOOT_SEC_OFFSET = 0x$(shell echo "obase=16; (($(FLASH_SIZE_KB) * 1024) - $(strip $(1)))" | bc)
+CALC_ADDRESS_IN_HEX = $(shell printf "0x%X" $$(( $(1) )) )
+BOOT_START_OFFSET = $(call CALC_ADDRESS_IN_HEX, ($(FLASH_SIZE_KB) - $(BOOT_SECTION_SIZE_KB)) * 1024 )
+BOOT_SEC_OFFSET = $(call CALC_ADDRESS_IN_HEX, ($(FLASH_SIZE_KB) * 1024) - $(strip $(1)) )