diff --git a/esp8266/main.c b/esp8266/main.c
index fe5fc81b6d..908a2c61a6 100644
--- a/esp8266/main.c
+++ b/esp8266/main.c
@@ -48,7 +48,9 @@ STATIC void mp_reset(void) {
     mp_init();
     mp_obj_list_init(mp_sys_path, 0);
     mp_obj_list_init(mp_sys_argv, 0);
+    #if MICROPY_VFS_FAT
     memset(MP_STATE_PORT(fs_user_mount), 0, sizeof(MP_STATE_PORT(fs_user_mount)));
+    #endif
     MP_STATE_PORT(mp_kbd_exception) = mp_obj_new_exception(&mp_type_KeyboardInterrupt);
 #if MICROPY_MODULE_FROZEN
     pyexec_frozen_module("boot");
@@ -77,11 +79,21 @@ mp_lexer_t *fat_vfs_lexer_new_from_file(const char *filename);
 mp_import_stat_t fat_vfs_import_stat(const char *path);
 
 mp_lexer_t *mp_lexer_new_from_file(const char *filename) {
+    #if MICROPY_VFS_FAT
     return fat_vfs_lexer_new_from_file(filename);
+    #else
+    (void)filename;
+    return NULL;
+    #endif
 }
 
 mp_import_stat_t mp_import_stat(const char *path) {
+    #if MICROPY_VFS_FAT
     return fat_vfs_import_stat(path);
+    #else
+    (void)path;
+    return MP_IMPORT_STAT_NO_EXIST;
+    #endif
 }
 
 mp_obj_t mp_builtin_open(uint n_args, const mp_obj_t *args, mp_map_t *kwargs) {
diff --git a/esp8266/moduos.c b/esp8266/moduos.c
index b70c5b9067..bef7cddc32 100644
--- a/esp8266/moduos.c
+++ b/esp8266/moduos.c
@@ -69,6 +69,7 @@ STATIC mp_obj_t os_uname(void) {
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_0(os_uname_obj, os_uname);
 
+#if MICROPY_VFS_FAT
 STATIC mp_obj_t vfs_proxy_call(qstr method_name, mp_uint_t n_args, const mp_obj_t *args) {
     if (MP_STATE_PORT(fs_user_mount)[0] == NULL) {
         nlr_raise(mp_obj_new_exception_arg1(&mp_type_OSError, MP_OBJ_NEW_SMALL_INT(ENODEV)));
@@ -89,14 +90,15 @@ STATIC mp_obj_t os_remove(mp_obj_t path_in) {
     return vfs_proxy_call(MP_QSTR_remove, 1, &path_in);
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_1(os_remove_obj, os_remove);
+#endif
 
 STATIC const mp_rom_map_elem_t os_module_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_uos) },
     { MP_ROM_QSTR(MP_QSTR_uname), MP_ROM_PTR(&os_uname_obj) },
-    { MP_ROM_QSTR(MP_QSTR_listdir), MP_ROM_PTR(&os_listdir_obj) },
-    { MP_ROM_QSTR(MP_QSTR_remove), MP_ROM_PTR(&os_remove_obj) },
     #if MICROPY_VFS_FAT
     { MP_ROM_QSTR(MP_QSTR_VfsFat), MP_ROM_PTR(&mp_fat_vfs_type) },
+    { MP_ROM_QSTR(MP_QSTR_listdir), MP_ROM_PTR(&os_listdir_obj) },
+    { MP_ROM_QSTR(MP_QSTR_remove), MP_ROM_PTR(&os_remove_obj) },
     #endif
 };