diff --git a/esp8266/modpyb.h b/esp8266/modpyb.h
index 5d5851a..641c8fc 100644
--- a/esp8266/modpyb.h
+++ b/esp8266/modpyb.h
@@ -1,2 +1,3 @@
 extern const mp_obj_type_t pyb_pin_type;
+extern const mp_obj_type_t pyb_adc_type;
 extern const mp_obj_base_t pyb_rtc_obj;