diff --git a/sys/dev/iwx/if_iwx.c b/sys/dev/iwx/if_iwx.c
--- a/sys/dev/iwx/if_iwx.c
+++ b/sys/dev/iwx/if_iwx.c
@@ -429,10 +429,9 @@
 static int	iwx_config_ltr(struct iwx_softc *);
 static void 	iwx_update_rx_desc(struct iwx_softc *, struct iwx_rx_ring *, int, bus_dma_segment_t *);
 static int 	iwx_rx_addbuf(struct iwx_softc *, int, int);
-static int	iwx_rxmq_get_signal_strength(struct iwx_softc *, struct iwx_rx_mpdu_desc *);
+static int8_t	iwx_rxmq_get_signal_strength(struct iwx_softc *, struct iwx_rx_mpdu_desc *);
 static void	iwx_rx_rx_phy_cmd(struct iwx_softc *, struct iwx_rx_packet *,
     struct iwx_rx_data *);
-static int	iwx_get_noise(const struct iwx_statistics_rx_non_phy *);
 static int	iwx_rx_hwdecrypt(struct iwx_softc *, struct mbuf *, uint32_t);
 #if 0
 int	iwx_ccmp_decap(struct iwx_softc *, struct mbuf *,
@@ -4176,11 +4175,11 @@
 	return 0;
 }
 
-static int
+static int8_t
 iwx_rxmq_get_signal_strength(struct iwx_softc *sc,
     struct iwx_rx_mpdu_desc *desc)
 {
-	int energy_a, energy_b;
+	int8_t energy_a, energy_b;
 
 	if (sc->sc_device_family >= IWX_DEVICE_FAMILY_AX210) {
 		energy_a = desc->v3.energy_a;
@@ -4189,8 +4188,8 @@
 		energy_a = desc->v1.energy_a;
 		energy_b = desc->v1.energy_b;
 	}
-	energy_a = energy_a ? -energy_a : -256;
-	energy_b = energy_b ? -energy_b : -256;
+	energy_a = energy_a ? -energy_a : INT8_MIN;
+	energy_b = energy_b ? -energy_b : INT8_MIN;
 	return MAX(energy_a, energy_b);
 }
 
@@ -4210,10 +4209,12 @@
 /*
  * Retrieve the average noise (in dBm) among receivers.
  */
-static int
+static uint8_t
 iwx_get_noise(const struct iwx_statistics_rx_non_phy *stats)
 {
-	int i, total, nbant, noise;
+	int i, nbant;
+	uint32_t total;
+	uint8_t noise;
 
 	total = nbant = noise = 0;
 	for (i = 0; i < 3; i++) {
@@ -4225,7 +4226,7 @@
 	}
 
 	/* There should be at least one antenna but check anyway. */
-	return (nbant == 0) ? -127 : (total / nbant) - 107;
+	return (nbant == 0) ? -127 : (-127 + (total / nbant));
 }
 
 #if 0
@@ -4479,7 +4480,7 @@
 	struct ieee80211_rx_stats rxs;
 	struct iwx_rx_mpdu_desc *desc;
 	uint32_t len, hdrlen, rate_n_flags, device_timestamp;
-	int rssi;
+	int8_t rssi;
 	uint8_t chanidx;
 	uint16_t phy_info;
 	size_t desc_size;
@@ -4622,8 +4623,6 @@
 	phy_info = le16toh(desc->phy_info);
 
 	rssi = iwx_rxmq_get_signal_strength(sc, desc);
-	rssi = (0 - IWX_MIN_DBM) + rssi;		/* normalize */
-	rssi = MIN(rssi, (IWX_MAX_DBM - IWX_MIN_DBM));	/* clip to max. 100% */
 
 	memset(&rxs, 0, sizeof(rxs));
 	rxs.r_flags |= IEEE80211_R_IEEE | IEEE80211_R_FREQ;
@@ -4639,9 +4638,18 @@
 	rxs.c_rx_tsf = device_timestamp;
 	rxs.c_chain = chanidx;
 
-	/* rssi is in 1/2db units */
-	rxs.c_rssi = rssi * 2;
+	/*
+	 * iwx_attach initialized sc_noise to be reasonably valid before
+	 * the first IWX_STATISTICS_NOTIFICATION with information.
+	 */
 	rxs.c_nf = sc->sc_noise;
+	if (rssi != 0) {
+		/* rssi is in 1/2db units relative to the NF. */
+		rxs.c_rssi = (rssi - sc->sc_noise) * 2;
+	} else {
+		/* Or we do not set IEEE80211_R_RSSI? */
+		rxs.c_rssi = rxs.c_nf;
+	}
 
 	if (pad) {
 		rxs.c_pktflags |= IEEE80211_RX_F_DECRYPTED;
@@ -10498,6 +10506,9 @@
 			mbufq_init(&rxba->entries[j].frames, ifqmaxlen);
 	}
 
+	/* Initialize to something to have a chance to get S:N values. */
+	sc->sc_noise = -127;
+
 	sc->sc_preinit_hook.ich_func = iwx_attach_hook;
 	sc->sc_preinit_hook.ich_arg = sc;
 	if (config_intrhook_establish(&sc->sc_preinit_hook) != 0) {
diff --git a/sys/dev/iwx/if_iwxvar.h b/sys/dev/iwx/if_iwxvar.h
--- a/sys/dev/iwx/if_iwxvar.h
+++ b/sys/dev/iwx/if_iwxvar.h
@@ -786,7 +786,7 @@
 	struct iwx_phy_ctxt sc_phyctxt[IWX_NUM_PHY_CTX];
 
 	struct iwx_notif_statistics sc_stats;
-	int sc_noise;
+	int8_t sc_noise;
 
 	int sc_pm_support;
 	int sc_ltr_enabled;