diff --git a/drivers/net/wireless/iwlwifi/iwl-agn-hcmd.c b/drivers/net/wireless/iwlwifi/iwl-agn-hcmd.c
index a63582f060f1..d86902b83630 100644
--- a/drivers/net/wireless/iwlwifi/iwl-agn-hcmd.c
+++ b/drivers/net/wireless/iwlwifi/iwl-agn-hcmd.c
@@ -321,7 +321,7 @@ static int iwlagn_set_pan_params(struct iwl_priv *priv)
 			bcnint = max_t(int, bcnint,
 				       ctx_bss->vif->bss_conf.beacon_int);
 		if (!bcnint)
-			bcnint = 100;
+			bcnint = DEFAULT_BEACON_INTERVAL;
 		slot0 = bcnint / 2;
 		slot1 = bcnint - slot0;
 
@@ -339,7 +339,7 @@ static int iwlagn_set_pan_params(struct iwl_priv *priv)
 		slot0 = 0;
 		slot1 = max_t(int, 1, ctx_pan->vif->bss_conf.dtim_period) *
 					ctx_pan->vif->bss_conf.beacon_int;
-		slot1 = max_t(int, 100, slot1);
+		slot1 = max_t(int, DEFAULT_BEACON_INTERVAL, slot1);
 
 		if (test_bit(STATUS_SCAN_HW, &priv->status)) {
 			slot0 = slot1 * 3 - 20;
diff --git a/drivers/net/wireless/iwlwifi/iwl-core.c b/drivers/net/wireless/iwlwifi/iwl-core.c
index c393b20ae1c1..c9c523b2883f 100644
--- a/drivers/net/wireless/iwlwifi/iwl-core.c
+++ b/drivers/net/wireless/iwlwifi/iwl-core.c
@@ -491,8 +491,29 @@ EXPORT_SYMBOL(iwl_is_ht40_tx_allowed);
 
 static u16 iwl_adjust_beacon_interval(u16 beacon_val, u16 max_beacon_val)
 {
-	u16 new_val = 0;
-	u16 beacon_factor = 0;
+	u16 new_val;
+	u16 beacon_factor;
+
+	/*
+	 * If mac80211 hasn't given us a beacon interval, program
+	 * the default into the device (not checking this here
+	 * would cause the adjustment below to return the maximum
+	 * value, which may break PAN.)
+	 */
+	if (!beacon_val)
+		return DEFAULT_BEACON_INTERVAL;
+
+	/*
+	 * If the beacon interval we obtained from the peer
+	 * is too large, we'll have to wake up more often
+	 * (and in IBSS case, we'll beacon too much)
+	 *
+	 * For example, if max_beacon_val is 4096, and the
+	 * requested beacon interval is 7000, we'll have to
+	 * use 3500 to be able to wake up on the beacons.
+	 *
+	 * This could badly influence beacon detection stats.
+	 */
 
 	beacon_factor = (beacon_val + max_beacon_val) / max_beacon_val;
 	new_val = beacon_val / beacon_factor;