--- a/ath/if_ath.c
+++ b/ath/if_ath.c
@@ -5495,6 +5495,8 @@
 		ath_hal_intrset(ah, sc->sc_imask);
 		ath_set_beacon_cal(sc, 0);
 	} else {
+		unsigned long flags;
+
 		ath_hal_intrset(ah, 0);
 		if (reset_tsf)
 			intval |= HAL_BEACON_RESET_TSF;
@@ -5514,11 +5516,14 @@
 		ath_beacon_dturbo_config(vap, intval &
 				~(HAL_BEACON_RESET_TSF | HAL_BEACON_ENA));
 #endif
+		local_irq_save(flags);
 		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);
+		local_irq_restore(flags);
+
 		if (intval & HAL_BEACON_RESET_TSF) {
 			sc->sc_last_tsf = 0;
 		}
