diff --git a/net/mac80211/util.c b/net/mac80211/util.c
index 3c61060..c76c9d7 100644
--- a/net/mac80211/util.c
+++ b/net/mac80211/util.c
@@ -2526,11 +2526,23 @@
 	struct ieee80211_local *local =
 		container_of(work, struct ieee80211_local, radar_detected_work);
 	struct cfg80211_chan_def chandef = local->hw.conf.chandef;
+	struct ieee80211_chanctx *ctx;
+	int num_chanctx = 0;
+
+	mutex_lock(&local->chanctx_mtx);
+	list_for_each_entry(ctx, &local->chanctx_list, list) {
+		if (ctx->replace_state == IEEE80211_CHANCTX_REPLACES_OTHER)
+			continue;
+
+		num_chanctx++;
+		chandef = ctx->conf.def;
+	}
+	mutex_unlock(&local->chanctx_mtx);
 
 	ieee80211_dfs_cac_cancel(local);
 
-	if (local->use_chanctx)
-		/* currently not handled */
+	if (num_chanctx > 1)
+		/* XXX: multi-channel is not supported yet */
 		WARN_ON(1);
 	else
 		cfg80211_radar_event(local->hw.wiphy, &chandef, GFP_KERNEL);