Index: head/sys/dev/usb/wlan/if_urtwn.c
===================================================================
--- head/sys/dev/usb/wlan/if_urtwn.c
+++ head/sys/dev/usb/wlan/if_urtwn.c
@@ -666,6 +666,7 @@
 			tap->wr_rate = 0x80 | (rate - 12);
 		}
 		tap->wr_dbm_antsignal = rssi;
+		tap->wr_dbm_antnoise = URTWN_NOISE_FLOOR;
 		tap->wr_chan_freq = htole16(ic->ic_curchan->ic_freq);
 		tap->wr_chan_flags = htole16(ic->ic_curchan->ic_flags);
 	}
Index: head/sys/dev/usb/wlan/if_urtwnvar.h
===================================================================
--- head/sys/dev/usb/wlan/if_urtwnvar.h
+++ head/sys/dev/usb/wlan/if_urtwnvar.h
@@ -37,14 +37,16 @@
 	uint8_t		wr_rate;
 	uint16_t	wr_chan_freq;
 	uint16_t	wr_chan_flags;
-	uint8_t		wr_dbm_antsignal;
+	int8_t		wr_dbm_antsignal;
+	int8_t		wr_dbm_antnoise;
 } __packed __aligned(8);
 
 #define URTWN_RX_RADIOTAP_PRESENT			\
 	(1 << IEEE80211_RADIOTAP_FLAGS |		\
 	 1 << IEEE80211_RADIOTAP_RATE |			\
 	 1 << IEEE80211_RADIOTAP_CHANNEL |		\
-	 1 << IEEE80211_RADIOTAP_DBM_ANTSIGNAL)
+	 1 << IEEE80211_RADIOTAP_DBM_ANTSIGNAL |	\
+	 1 << IEEE80211_RADIOTAP_DBM_ANTNOISE)
 
 struct urtwn_tx_radiotap_header {
 	struct ieee80211_radiotap_header wt_ihdr;