--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -670,6 +670,8 @@ static u32 ieee80211_handle_bss_capabili
 	}
 
 	use_short_slot = !!(capab & WLAN_CAPABILITY_SHORT_SLOT_TIME);
+	if (sdata->local->hw.conf.channel->band == IEEE80211_BAND_5GHZ)
+		use_short_slot = true;
 
 	if (use_protection != bss_conf->use_cts_prot) {
 		bss_conf->use_cts_prot = use_protection;
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -1087,6 +1087,13 @@ static int ieee80211_change_bss(struct w
 			params->use_short_preamble;
 		changed |= BSS_CHANGED_ERP_PREAMBLE;
 	}
+
+	if (!sdata->vif.bss_conf.use_short_slot &&
+	    sdata->local->hw.conf.channel->band == IEEE80211_BAND_5GHZ) {
+		sdata->vif.bss_conf.use_short_slot = true;
+		changed |= BSS_CHANGED_ERP_SLOT;
+	}
+
 	if (params->use_short_slot_time >= 0) {
 		sdata->vif.bss_conf.use_short_slot =
 			params->use_short_slot_time;