diff --git a/hw/net/ftgmac100.c b/hw/net/ftgmac100.c
index 280aa3d3a1..7c9fa720df 100644
--- a/hw/net/ftgmac100.c
+++ b/hw/net/ftgmac100.c
@@ -481,6 +481,37 @@ static int ftgmac100_write_bd(FTGMAC100Desc *bd, dma_addr_t addr)
     return 0;
 }
 
+static int ftgmac100_insert_vlan(FTGMAC100State *s, int frame_size,
+                                  uint8_t vlan_tci)
+{
+    uint8_t *vlan_hdr = s->frame + (ETH_ALEN * 2);
+    uint8_t *payload = vlan_hdr + sizeof(struct vlan_header);
+
+    if (frame_size < sizeof(struct eth_header)) {
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: frame too small for VLAN insertion : %d bytes\n",
+                      __func__, frame_size);
+        s->isr |= FTGMAC100_INT_XPKT_LOST;
+        goto out;
+    }
+
+    if (frame_size + sizeof(struct vlan_header) > sizeof(s->frame)) {
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: frame too big : %d bytes\n",
+                      __func__, frame_size);
+        s->isr |= FTGMAC100_INT_XPKT_LOST;
+        frame_size -= sizeof(struct vlan_header);
+    }
+
+    memmove(payload, vlan_hdr, frame_size - (ETH_ALEN * 2));
+    stw_be_p(vlan_hdr, ETH_P_VLAN);
+    stw_be_p(vlan_hdr + 2, vlan_tci);
+    frame_size += sizeof(struct vlan_header);
+
+out:
+    return frame_size;
+}
+
 static void ftgmac100_do_tx(FTGMAC100State *s, uint32_t tx_ring,
                             uint32_t tx_descriptor)
 {
@@ -530,25 +561,17 @@ static void ftgmac100_do_tx(FTGMAC100State *s, uint32_t tx_ring,
             break;
         }
 
-        /* Check for VLAN */
-        if (bd.des0 & FTGMAC100_TXDES0_FTS &&
-            bd.des1 & FTGMAC100_TXDES1_INS_VLANTAG &&
-            be16_to_cpu(PKT_GET_ETH_HDR(ptr)->h_proto) != ETH_P_VLAN) {
-            if (frame_size + len + 4 > sizeof(s->frame)) {
-                qemu_log_mask(LOG_GUEST_ERROR, "%s: frame too big : %d bytes\n",
-                              __func__, len);
-                s->isr |= FTGMAC100_INT_XPKT_LOST;
-                len =  sizeof(s->frame) - frame_size - 4;
-            }
-            memmove(ptr + 16, ptr + 12, len - 12);
-            stw_be_p(ptr + 12, ETH_P_VLAN);
-            stw_be_p(ptr + 14, bd.des1);
-            len += 4;
-        }
-
         ptr += len;
         frame_size += len;
         if (bd.des0 & FTGMAC100_TXDES0_LTS) {
+
+            /* Check for VLAN */
+            if (flags & FTGMAC100_TXDES1_INS_VLANTAG &&
+                be16_to_cpu(PKT_GET_ETH_HDR(s->frame)->h_proto) != ETH_P_VLAN) {
+                frame_size = ftgmac100_insert_vlan(s, frame_size,
+                                            FTGMAC100_TXDES1_VLANTAG_CI(flags));
+            }
+
             if (flags & FTGMAC100_TXDES1_IP_CHKSUM) {
                 net_checksum_calculate(s->frame, frame_size);
             }