diff --git a/src/drivers/driver.h b/src/drivers/driver.h
index d34c6794f..4ac9f16a0 100644
--- a/src/drivers/driver.h
+++ b/src/drivers/driver.h
@@ -1913,8 +1913,21 @@ enum chan_width {
 	CHAN_WIDTH_UNKNOWN
 };
 
+#define WPA_INVALID_NOISE 9999
+
 /**
  * struct wpa_signal_info - Information about channel signal quality
+ * @frequency: control frequency
+ * @above_threshold: true if the above threshold was crossed
+ *	(relevant for a CQM event)
+ * @current_signal: in dBm
+ * @avg_signal: in dBm
+ * @avg_beacon_signal: in dBm
+ * @current_noise: %WPA_INVALID_NOISE if not supported
+ * @current_txrate: current TX rate
+ * @chanwidth: channel width
+ * @center_frq1: center frequency for the first segment
+ * @center_frq2: center frequency for the second segment (if relevant)
  */
 struct wpa_signal_info {
 	u32 frequency;
diff --git a/src/drivers/driver_nl80211.c b/src/drivers/driver_nl80211.c
index 771e76696..b2c4120eb 100644
--- a/src/drivers/driver_nl80211.c
+++ b/src/drivers/driver_nl80211.c
@@ -1469,7 +1469,7 @@ int nl80211_get_link_signal(struct wpa_driver_nl80211_data *drv,
 {
 	struct nl_msg *msg;
 
-	sig->current_signal = -9999;
+	sig->current_signal = -WPA_INVALID_NOISE;
 	sig->current_txrate = 0;
 
 	if (!(msg = nl80211_drv_msg(drv, 0, NL80211_CMD_GET_STATION)) ||
@@ -1531,7 +1531,7 @@ int nl80211_get_link_noise(struct wpa_driver_nl80211_data *drv,
 {
 	struct nl_msg *msg;
 
-	sig_change->current_noise = 9999;
+	sig_change->current_noise = WPA_INVALID_NOISE;
 	sig_change->frequency = drv->assoc_freq;
 
 	msg = nl80211_drv_msg(drv, NLM_F_DUMP, NL80211_CMD_GET_SURVEY);
diff --git a/src/drivers/driver_wext.c b/src/drivers/driver_wext.c
index 933b8d986..20abaab4c 100644
--- a/src/drivers/driver_wext.c
+++ b/src/drivers/driver_wext.c
@@ -2428,8 +2428,8 @@ static int wpa_driver_wext_signal_poll(void *priv, struct wpa_signal_info *si)
 	struct iwreq iwr;
 
 	os_memset(si, 0, sizeof(*si));
-	si->current_signal = -9999;
-	si->current_noise = 9999;
+	si->current_signal = -WPA_INVALID_NOISE;
+	si->current_noise = WPA_INVALID_NOISE;
 	si->chanwidth = CHAN_WIDTH_UNKNOWN;
 
 	os_memset(&iwr, 0, sizeof(iwr));