diff --git a/hardware/esp8266com/esp8266/cores/esp8266/core_esp8266_wiring_pwm.c b/hardware/esp8266com/esp8266/cores/esp8266/core_esp8266_wiring_pwm.c
index b175f6e55..c74f76bc3 100644
--- a/hardware/esp8266com/esp8266/cores/esp8266/core_esp8266_wiring_pwm.c
+++ b/hardware/esp8266com/esp8266/cores/esp8266/core_esp8266_wiring_pwm.c
@@ -81,8 +81,8 @@ void prep_pwm_steps(){
 	}
 	ETS_FRC1_INTR_DISABLE();
 	pwm_steps_len = pwm_temp_steps_len;
-	os_memcpy(pwm_steps, pwm_temp_steps, (pwm_temp_steps_len + 1) * 2);
-	os_memcpy(pwm_steps_mask, pwm_temp_masks, pwm_temp_steps_len * 4);
+	ets_memcpy(pwm_steps, pwm_temp_steps, (pwm_temp_steps_len + 1) * 2);
+	ets_memcpy(pwm_steps_mask, pwm_temp_masks, pwm_temp_steps_len * 4);
 	pwm_multiplier = F_CPU/(PWMRANGE * pwm_freq);
 	ETS_FRC1_INTR_ENABLE();
 }