--- a/ath/if_ath.c
+++ b/ath/if_ath.c
@@ -5476,6 +5476,9 @@
 		ath_beacon_dturbo_config(vap, intval &
 				~(HAL_BEACON_RESET_TSF | HAL_BEACON_ENA));
 #endif
+		if ((nexttbtt & HAL_BEACON_PERIOD) - (ath_hal_gettsf32(ah) >> 10)
+				<= ath_hal_sw_beacon_response_time)
+			nexttbtt += intval;
 		sc->sc_nexttbtt = nexttbtt;
 		ath_hal_beaconinit(ah, nexttbtt, intval);
 		if (intval & HAL_BEACON_RESET_TSF) {
--- a/ath_hal/ah_os.c
+++ b/ath_hal/ah_os.c
@@ -71,6 +71,7 @@
 int	ath_hal_dma_beacon_response_time = 2;	/* in TUs */
 int	ath_hal_sw_beacon_response_time = 10;	/* in TUs */
 int	ath_hal_additional_swba_backoff = 0;	/* in TUs */
+EXPORT_SYMBOL(ath_hal_sw_beacon_response_time);
 
 struct ath_hal *
 _ath_hal_attach(u_int16_t devid, HAL_SOFTC sc,
