diff --git a/sys/dev/rtwn/rtl8192c/r92c_tx.c b/sys/dev/rtwn/rtl8192c/r92c_tx.c
index 840335a86983..f91f89da3320 100644
--- a/sys/dev/rtwn/rtl8192c/r92c_tx.c
+++ b/sys/dev/rtwn/rtl8192c/r92c_tx.c
@@ -103,7 +103,7 @@ r92c_tx_protection(struct rtwn_softc *sc, struct r92c_tx_desc *txd,
 			rate = rtwn_ctl_mcsrate(ic->ic_rt, ridx);
 		else
 			rate = ieee80211_ctl_rate(ic->ic_rt, ridx2rate[ridx]);
-		ridx = rate2ridx(rate);
+		ridx = rate2ridx(IEEE80211_RV(rate));
 
 		txd->txdw4 |= htole32(SM(R92C_TXDW4_RTSRATE, ridx));
 		/* RTS rate fallback limit (max). */
diff --git a/sys/dev/rtwn/rtl8812a/r12a_tx.c b/sys/dev/rtwn/rtl8812a/r12a_tx.c
index 3f6888c07ff7..9c8b27b233f3 100644
--- a/sys/dev/rtwn/rtl8812a/r12a_tx.c
+++ b/sys/dev/rtwn/rtl8812a/r12a_tx.c
@@ -111,7 +111,7 @@ r12a_tx_protection(struct rtwn_softc *sc, struct r12a_tx_desc *txd,
 			rate = rtwn_ctl_mcsrate(ic->ic_rt, ridx);
 		else
 			rate = ieee80211_ctl_rate(ic->ic_rt, ridx2rate[ridx]);
-		ridx = rate2ridx(rate);
+		ridx = rate2ridx(IEEE80211_RV(rate));
 
 		txd->txdw4 |= htole32(SM(R12A_TXDW4_RTSRATE, ridx));
 		/* RTS rate fallback limit (max). */