diff --git a/drivers/net/ethernet/cavium/thunder/nic.h b/drivers/net/ethernet/cavium/thunder/nic.h
index 376a96bce33f..227343625e83 100644
--- a/drivers/net/ethernet/cavium/thunder/nic.h
+++ b/drivers/net/ethernet/cavium/thunder/nic.h
@@ -577,10 +577,8 @@ struct set_ptp {
 
 struct xcast {
 	u8    msg;
-	union {
-		u8    mode;
-		u64   mac;
-	} data;
+	u8    mode;
+	u64   mac:48;
 };
 
 /* 128 bit shared memory between PF and each VF */
diff --git a/drivers/net/ethernet/cavium/thunder/nic_main.c b/drivers/net/ethernet/cavium/thunder/nic_main.c
index 90497a27df18..620dbe082ca0 100644
--- a/drivers/net/ethernet/cavium/thunder/nic_main.c
+++ b/drivers/net/ethernet/cavium/thunder/nic_main.c
@@ -1094,7 +1094,7 @@ static void nic_handle_mbx_intr(struct nicpf *nic, int vf)
 		bgx = NIC_GET_BGX_FROM_VF_LMAC_MAP(nic->vf_lmac_map[vf]);
 		lmac = NIC_GET_LMAC_FROM_VF_LMAC_MAP(nic->vf_lmac_map[vf]);
 		bgx_set_dmac_cam_filter(nic->node, bgx, lmac,
-					mbx.xcast.data.mac,
+					mbx.xcast.mac,
 					vf < NIC_VF_PER_MBX_REG ? vf :
 					vf - NIC_VF_PER_MBX_REG);
 		break;
@@ -1106,7 +1106,7 @@ static void nic_handle_mbx_intr(struct nicpf *nic, int vf)
 		}
 		bgx = NIC_GET_BGX_FROM_VF_LMAC_MAP(nic->vf_lmac_map[vf]);
 		lmac = NIC_GET_LMAC_FROM_VF_LMAC_MAP(nic->vf_lmac_map[vf]);
-		bgx_set_xcast_mode(nic->node, bgx, lmac, mbx.xcast.data.mode);
+		bgx_set_xcast_mode(nic->node, bgx, lmac, mbx.xcast.mode);
 		break;
 	default:
 		dev_err(&nic->pdev->dev,
diff --git a/drivers/net/ethernet/cavium/thunder/nicvf_main.c b/drivers/net/ethernet/cavium/thunder/nicvf_main.c
index 45f06504a61b..da5986ca7bee 100644
--- a/drivers/net/ethernet/cavium/thunder/nicvf_main.c
+++ b/drivers/net/ethernet/cavium/thunder/nicvf_main.c
@@ -1961,7 +1961,7 @@ static void __nicvf_set_rx_mode_task(u8 mode, struct xcast_addr_list *mc_addrs,
 		 * its' own LMAC to the filter to accept packets for it.
 		 */
 		mbx.xcast.msg = NIC_MBOX_MSG_ADD_MCAST;
-		mbx.xcast.data.mac = 0;
+		mbx.xcast.mac = 0;
 		if (nicvf_send_msg_to_pf(nic, &mbx) < 0)
 			goto free_mc;
 	}
@@ -1971,7 +1971,7 @@ static void __nicvf_set_rx_mode_task(u8 mode, struct xcast_addr_list *mc_addrs,
 		/* now go through kernel list of MACs and add them one by one */
 		for (idx = 0; idx < mc_addrs->count; idx++) {
 			mbx.xcast.msg = NIC_MBOX_MSG_ADD_MCAST;
-			mbx.xcast.data.mac = mc_addrs->mc[idx];
+			mbx.xcast.mac = mc_addrs->mc[idx];
 			if (nicvf_send_msg_to_pf(nic, &mbx) < 0)
 				goto free_mc;
 		}
@@ -1979,7 +1979,7 @@ static void __nicvf_set_rx_mode_task(u8 mode, struct xcast_addr_list *mc_addrs,
 
 	/* and finally set rx mode for PF accordingly */
 	mbx.xcast.msg = NIC_MBOX_MSG_SET_XCAST;
-	mbx.xcast.data.mode = mode;
+	mbx.xcast.mode = mode;
 
 	nicvf_send_msg_to_pf(nic, &mbx);
 free_mc: