diff --git a/nimble/include/nimble/hci_common.h b/nimble/include/nimble/hci_common.h
index 437ed84cf..420c9fc12 100644
--- a/nimble/include/nimble/hci_common.h
+++ b/nimble/include/nimble/hci_common.h
@@ -941,7 +941,7 @@ struct hci_ext_adv_report_param {
     uint8_t prim_phy;
     uint8_t sec_phy;
     uint8_t sid;
-    uint8_t tx_power;
+    int8_t tx_power;
     int8_t rssi;
     uint16_t per_adv_itvl;
     uint8_t dir_addr_type;