diff --git a/ports/espressif/common-hal/wifi/Radio.c b/ports/espressif/common-hal/wifi/Radio.c
index 9715894f78..ac997cc0b7 100644
--- a/ports/espressif/common-hal/wifi/Radio.c
+++ b/ports/espressif/common-hal/wifi/Radio.c
@@ -139,7 +139,7 @@ void common_hal_wifi_radio_set_mac_address(wifi_radio_obj_t *self, const uint8_t
     esp_wifi_set_mac(ESP_IF_WIFI_STA, mac);
 }
 
-float common_hal_wifi_radio_get_tx_power(wifi_radio_obj_t *self) {
+mp_float_t common_hal_wifi_radio_get_tx_power(wifi_radio_obj_t *self) {
     int8_t tx_power;
     esp_wifi_get_max_tx_power(&tx_power);
     return tx_power / 4.0;