diff --git a/sys/net80211/ieee80211_amrr.c b/sys/net80211/ieee80211_amrr.c
--- a/sys/net80211/ieee80211_amrr.c
+++ b/sys/net80211/ieee80211_amrr.c
@@ -132,8 +132,9 @@
 static void
 amrr_deinit(struct ieee80211vap *vap)
 {
-	IEEE80211_FREE(vap->iv_rs, M_80211_RATECTL);
 	KASSERT(nrefs > 0, ("imbalanced attach/detach"));
+	IEEE80211_FREE(vap->iv_rs, M_80211_RATECTL);
+	vap->iv_rs = NULL;	/* guard */
 	nrefs--;		/* XXX locking */
 }