diff --git a/sys/dev/usb/wlan/if_rsu.c b/sys/dev/usb/wlan/if_rsu.c
--- a/sys/dev/usb/wlan/if_rsu.c
+++ b/sys/dev/usb/wlan/if_rsu.c
@@ -576,6 +576,7 @@
 		ic->ic_rxstream = sc->sc_nrxstream;
 	}
 	ic->ic_flags_ext |= IEEE80211_FEXT_SCAN_OFFLOAD;
+	ic->ic_flags_ext |= IEEE80211_FEXT_SEQNO_OFFLOAD;
 
 	rsu_getradiocaps(ic, IEEE80211_CHAN_MAX, &ic->ic_nchans,
 	    ic->ic_channels);
@@ -2782,6 +2783,9 @@
 	if (rate != 0)
 		ridx = rate2ridx(rate);
 
+	/* Assign sequence number, A-MPDU or otherwise */
+	ieee80211_output_seqno_assign(ni, -1, m0);
+
 	if (wh->i_fc[1] & IEEE80211_FC1_PROTECTED) {
 		k = ieee80211_crypto_encap(ni, m0);
 		if (k == NULL) {