diff --git a/drivers/net/wireless/ath/ath9k/hw.c b/drivers/net/wireless/ath/ath9k/hw.c
index a43934fb81388b85fa966e738f39bf61a110e57d..4dddffd7c4038ebd87617ede8c68277bd44ef4eb 100644
--- a/drivers/net/wireless/ath/ath9k/hw.c
+++ b/drivers/net/wireless/ath/ath9k/hw.c
@@ -1020,7 +1020,7 @@ void ath9k_hw_init_global_settings(struct ath_hw *ah)
 	struct ath_common *common = ath9k_hw_common(ah);
 	struct ieee80211_conf *conf = &common->hw->conf;
 	const struct ath9k_channel *chan = ah->curchan;
-	int acktimeout, ctstimeout;
+	int acktimeout, ctstimeout, ack_offset = 0;
 	int slottime;
 	int sifstime;
 	int rx_lat = 0, tx_lat = 0, eifs = 0;
@@ -1054,6 +1054,7 @@ void ath9k_hw_init_global_settings(struct ath_hw *ah)
 		    tx_lat += 11;
 
 		sifstime *= 2;
+		ack_offset = 16;
 		slottime = 13;
 	} else if (IS_CHAN_QUARTER_RATE(chan)) {
 		eifs = 340;
@@ -1063,6 +1064,7 @@ void ath9k_hw_init_global_settings(struct ath_hw *ah)
 		    tx_lat += 22;
 
 		sifstime *= 4;
+		ack_offset = 32;
 		slottime = 21;
 	} else {
 		if (AR_SREV_9287(ah) && AR_SREV_9287_13_OR_LATER(ah)) {
@@ -1080,7 +1082,7 @@ void ath9k_hw_init_global_settings(struct ath_hw *ah)
 	}
 
 	/* As defined by IEEE 802.11-2007 17.3.8.6 */
-	acktimeout = slottime + sifstime + 3 * ah->coverage_class;
+	acktimeout = slottime + sifstime + 3 * ah->coverage_class + ack_offset;
 	ctstimeout = acktimeout;
 
 	/*
@@ -1090,7 +1092,8 @@ void ath9k_hw_init_global_settings(struct ath_hw *ah)
 	 * BA frames in some implementations, but it has been found to fix ACK
 	 * timeout issues in other cases as well.
 	 */
-	if (conf->channel && conf->channel->band == IEEE80211_BAND_2GHZ) {
+	if (conf->channel && conf->channel->band == IEEE80211_BAND_2GHZ &&
+	    !IS_CHAN_HALF_RATE(chan) && !IS_CHAN_QUARTER_RATE(chan)) {
 		acktimeout += 64 - sifstime - ah->slottime;
 		ctstimeout += 48 - sifstime - ah->slottime;
 	}