diff --git a/drivers/staging/rtl8723au/core/rtw_wlan_util.c b/drivers/staging/rtl8723au/core/rtw_wlan_util.c
index ab9d98d5fc7eee58dab00c0abe360f61a2e2d025..d675891ad23eccf435f0ea75ebf31ee66eb1408e 100644
--- a/drivers/staging/rtl8723au/core/rtw_wlan_util.c
+++ b/drivers/staging/rtl8723au/core/rtw_wlan_util.c
@@ -1562,22 +1562,19 @@ void update_capinfo23a(struct rtw_adapter *Adapter, u16 updateCap)
 {
 	struct mlme_ext_priv	*pmlmeext = &Adapter->mlmeextpriv;
 	struct mlme_ext_info *pmlmeinfo = &pmlmeext->mlmext_info;
-	bool		ShortPreamble;
 
 	if (updateCap & cShortPreamble) {
 		/*  Short Preamble */
 		if (pmlmeinfo->preamble_mode != PREAMBLE_SHORT) {
 			/*  PREAMBLE_LONG or PREAMBLE_AUTO */
-			ShortPreamble = true;
 			pmlmeinfo->preamble_mode = PREAMBLE_SHORT;
-			rtw_hal_set_hwreg23a(Adapter, HW_VAR_ACK_PREAMBLE, (u8 *)&ShortPreamble);
+			rtl8723a_ack_preamble(Adapter, true);
 		}
 	} else { /*  Long Preamble */
 		if (pmlmeinfo->preamble_mode != PREAMBLE_LONG) {
 			/*  PREAMBLE_SHORT or PREAMBLE_AUTO */
-			ShortPreamble = false;
 			pmlmeinfo->preamble_mode = PREAMBLE_LONG;
-			rtw_hal_set_hwreg23a(Adapter, HW_VAR_ACK_PREAMBLE, (u8 *)&ShortPreamble);
+			rtl8723a_ack_preamble(Adapter, false);
 		}
 	}
 	if (updateCap & cIBSS) {
diff --git a/drivers/staging/rtl8723au/hal/rtl8723a_hal_init.c b/drivers/staging/rtl8723au/hal/rtl8723a_hal_init.c
index 27752fd30c7e77ca008666b00b7710d111c8f312..fba69da87dd42ce285dd1ab0a50b001ff5628eb9 100644
--- a/drivers/staging/rtl8723au/hal/rtl8723a_hal_init.c
+++ b/drivers/staging/rtl8723au/hal/rtl8723a_hal_init.c
@@ -3143,10 +3143,6 @@ void SetHwReg8723A(struct rtw_adapter *padapter, u8 variable, u8 *val)
 		rtl8723a_set_bcn_func(padapter, *val);
 		break;
 
-	case HW_VAR_ACK_PREAMBLE:
-		rtl8723a_ack_preamble(padapter, *val);
-		break;
-
 	case HW_VAR_SEC_CFG:
 		rtl8723a_set_sec_cfg(padapter, *val);
 		break;
diff --git a/drivers/staging/rtl8723au/include/hal_intf.h b/drivers/staging/rtl8723au/include/hal_intf.h
index 81ebefea01571c793ee4c92a32c65403e104c457..b63643641e6275ba1d1e9d6f148ec7255c11ec92 100644
--- a/drivers/staging/rtl8723au/include/hal_intf.h
+++ b/drivers/staging/rtl8723au/include/hal_intf.h
@@ -39,7 +39,6 @@ enum HW_VARIABLES {
 	HW_VAR_INIT_RTS_RATE,
 	HW_VAR_TXPAUSE,
 	HW_VAR_BCN_FUNC,
-	HW_VAR_ACK_PREAMBLE,
 	HW_VAR_SEC_CFG,
 	HW_VAR_RF_TYPE,
 	HW_VAR_DM_FLAG,