--- a/net80211/ieee80211_beacon.c
+++ b/net80211/ieee80211_beacon.c
@@ -476,6 +476,14 @@ ieee80211_beacon_update(struct ieee80211
 			tie->tim_bitctl |= BITCTL_BUFD_MCAST;
 		else
 			tie->tim_bitctl &= ~BITCTL_BUFD_MCAST;
+
+		/* WAR: on some platforms, a race condition between beacon
+		 * contents update and beacon transmission leads to beacon
+		 * data not being updated in time. For most fields this is
+		 * not critical, but for powersave it is. Work around this
+		 * by always remapping the beacon when the TIM IE changes.
+		 */
+		len_changed = 1;
 	}
 
 	/* Whenever we want to switch to a new channel, we need to follow the
