diff --git a/ports/esp8266/modesp.c b/ports/esp8266/modesp.c
index 0e2acaf5ff..a6084e48bc 100644
--- a/ports/esp8266/modesp.c
+++ b/ports/esp8266/modesp.c
@@ -379,3 +379,5 @@ const mp_obj_module_t esp_module = {
     .base = { &mp_type_module },
     .globals = (mp_obj_dict_t *)&esp_module_globals,
 };
+
+MP_REGISTER_MODULE(MP_QSTR_esp, esp_module, 1);
diff --git a/ports/esp8266/modutime.c b/ports/esp8266/modutime.c
index 1d4ecc05f2..7f498ef1ed 100644
--- a/ports/esp8266/modutime.c
+++ b/ports/esp8266/modutime.c
@@ -129,3 +129,5 @@ const mp_obj_module_t utime_module = {
     .base = { &mp_type_module },
     .globals = (mp_obj_dict_t *)&time_module_globals,
 };
+
+MP_REGISTER_MODULE(MP_QSTR_utime, utime_module, 1);
diff --git a/ports/esp8266/mpconfigport.h b/ports/esp8266/mpconfigport.h
index 63577e7b08..a64bc8f86d 100644
--- a/ports/esp8266/mpconfigport.h
+++ b/ports/esp8266/mpconfigport.h
@@ -159,14 +159,6 @@ extern const struct _mp_print_t mp_debug_print;
 #define MICROPY_PORT_BUILTINS \
     { MP_ROM_QSTR(MP_QSTR_open), MP_ROM_PTR(&mp_builtin_open_obj) },
 
-// extra built in modules to add to the list of known ones
-extern const struct _mp_obj_module_t esp_module;
-extern const struct _mp_obj_module_t utime_module;
-
-#define MICROPY_PORT_BUILTIN_MODULES \
-    { MP_ROM_QSTR(MP_QSTR_esp), MP_ROM_PTR(&esp_module) }, \
-    { MP_ROM_QSTR(MP_QSTR_utime), MP_ROM_PTR(&utime_module) }, \
-
 #define MP_STATE_PORT MP_STATE_VM
 
 #define MICROPY_PORT_ROOT_POINTERS \