diff --git a/sys/dev/rtwn/rtl8192c/r92c_tx.c b/sys/dev/rtwn/rtl8192c/r92c_tx.c
--- a/sys/dev/rtwn/rtl8192c/r92c_tx.c
+++ b/sys/dev/rtwn/rtl8192c/r92c_tx.c
@@ -267,10 +267,24 @@
 			rtwn_r92c_tx_enable_ampdu(sc, buf,
 			    (m->m_flags & M_AMPDU_MPDU) != 0);
 			if (m->m_flags & M_AMPDU_MPDU) {
+				struct ieee80211_tx_ampdu *tap =
+				    &ni->ni_tx_ampdu[tid];
+				int wnd;
+
 				txd->txdw2 |= htole32(SM(R92C_TXDW2_AMPDU_DEN,
-				    vap->iv_ampdu_density));
+				    ieee80211_ht_get_node_ampdu_density(ni)));
+				/*
+				 * BAW is (MAX_AGG * 2) + 1, hence the / 2
+				 * here.  Ensure we don't send 0 or more than
+				 * 31.
+				 */
+				wnd = tap->txa_wnd / 2;
+				if (wnd == 0)
+					wnd = 1;
+				if (wnd > 0x1f)
+					wnd = 0x1f;
 				txd->txdw6 |= htole32(SM(R92C_TXDW6_MAX_AGG,
-				    0x1f));	/* XXX */
+				    wnd));
 			}
 			if (sc->sc_ratectl == RTWN_RATECTL_NET80211) {
 				txd->txdw2 |= htole32(R92C_TXDW2_CCX_RPT);
diff --git a/sys/dev/rtwn/rtl8812a/r12a_tx.c b/sys/dev/rtwn/rtl8812a/r12a_tx.c
--- a/sys/dev/rtwn/rtl8812a/r12a_tx.c
+++ b/sys/dev/rtwn/rtl8812a/r12a_tx.c
@@ -270,11 +270,25 @@
 			qsel = tid % RTWN_MAX_TID;
 
 			if (m->m_flags & M_AMPDU_MPDU) {
+				struct ieee80211_tx_ampdu *tap =
+				    &ni->ni_tx_ampdu[tid];
+				int wnd;
+
 				txd->txdw2 |= htole32(R12A_TXDW2_AGGEN);
 				txd->txdw2 |= htole32(SM(R12A_TXDW2_AMPDU_DEN,
-				    vap->iv_ampdu_density));
+				    ieee80211_ht_get_node_ampdu_density(ni)));
+				/*
+				 * BAW is (MAX_AGG * 2) + 1, hence the / 2
+				 * here.  Ensure we don't send 0 or more than
+				 * 31.
+				 */
+				wnd = tap->txa_wnd / 2;
+				if (wnd == 0)
+					wnd = 1;
+				if (wnd > 0x1f)
+					wnd = 0x1f;
 				txd->txdw3 |= htole32(SM(R12A_TXDW3_MAX_AGG,
-				    0x1f));	/* XXX */
+				    wnd));
 			} else
 				txd->txdw2 |= htole32(R12A_TXDW2_AGGBK);