--- /dev/null
+diff -urN madwifi-ng-refcount-r2313-20070505.old/net80211/ieee80211_beacon.c madwifi-ng-refcount-r2313-20070505.dev/net80211/ieee80211_beacon.c
+--- madwifi-ng-refcount-r2313-20070505.old/net80211/ieee80211_beacon.c 2007-05-13 18:17:56.687951160 +0200
++++ madwifi-ng-refcount-r2313-20070505.dev/net80211/ieee80211_beacon.c 2007-05-13 18:17:56.971907992 +0200
+@@ -512,7 +512,7 @@
+ vap->iv_flags &= ~IEEE80211_F_XRUPDATE;
+ }
+ #endif
+- if (ic->ic_flags_ext & IEEE80211_FEXT_ERPUPDATE) {
++ if ((ic->ic_flags_ext & IEEE80211_FEXT_ERPUPDATE) && (bo->bo_erp != NULL)) {
+ (void) ieee80211_add_erp(bo->bo_erp, ic);
+ ic->ic_flags_ext &= ~IEEE80211_FEXT_ERPUPDATE;
+ }