diff --git a/ports/esp8266/boards/GENERIC/mpconfigboard.mk b/ports/esp8266/boards/GENERIC/mpconfigboard.mk
index 2ecfb6d34..686131721 100644
--- a/ports/esp8266/boards/GENERIC/mpconfigboard.mk
+++ b/ports/esp8266/boards/GENERIC/mpconfigboard.mk
@@ -1,7 +1,7 @@
 LD_FILES = boards/esp8266_2m.ld
 
-MICROPY_PY_BTREE = 1
-MICROPY_VFS_FAT = 1
-MICROPY_VFS_LFS2 = 1
+MICROPY_PY_BTREE ?= 1
+MICROPY_VFS_FAT ?= 1
+MICROPY_VFS_LFS2 ?= 1
 
 FROZEN_MANIFEST ?= $(BOARD_DIR)/manifest.py
diff --git a/ports/esp8266/boards/GENERIC_1M/mpconfigboard.mk b/ports/esp8266/boards/GENERIC_1M/mpconfigboard.mk
index 7399790e7..fdbb0d824 100644
--- a/ports/esp8266/boards/GENERIC_1M/mpconfigboard.mk
+++ b/ports/esp8266/boards/GENERIC_1M/mpconfigboard.mk
@@ -1,4 +1,4 @@
 LD_FILES = boards/esp8266_1m.ld
 
-MICROPY_PY_BTREE = 1
-MICROPY_VFS_LFS2 = 1
+MICROPY_PY_BTREE ?= 1
+MICROPY_VFS_LFS2 ?= 1