const struct ieee80211_regdomain *regd)
 {
        enum ieee80211_band band;
+       unsigned int bands_set = 0;
 
        mutex_lock(&cfg80211_mutex);
        for (band = 0; band < IEEE80211_NUM_BANDS; band++) {
-               if (wiphy->bands[band])
-                       handle_band_custom(wiphy, band, regd);
+               if (!wiphy->bands[band])
+                       continue;
+               handle_band_custom(wiphy, band, regd);
+               bands_set++;
        }
        mutex_unlock(&cfg80211_mutex);
+
+       /*
+        * no point in calling this if it won't have any effect
+        * on your device's supportd bands.
+        */
+       WARN_ON(!bands_set);
 }
 EXPORT_SYMBOL(wiphy_apply_custom_regulatory);