diff --git a/esp8266/Makefile b/esp8266/Makefile
index 65a513afd6..1586c576ca 100644
--- a/esp8266/Makefile
+++ b/esp8266/Makefile
@@ -18,7 +18,7 @@ FROZEN_MPY_DIR = modules
 PORT ?= /dev/ttyACM0
 BAUD ?= 115200
 FLASH_MODE ?= qio
-FLASH_SIZE ?= 8m
+FLASH_SIZE ?= detect
 CROSS_COMPILE = xtensa-lx106-elf-
 ESP_SDK = $(shell $(CC) -print-sysroot)/usr