diff --git a/components/bt/esp_ble_mesh/btc/btc_ble_mesh_prov.c b/components/bt/esp_ble_mesh/btc/btc_ble_mesh_prov.c
index eb7e543368..b9c9448748 100644
--- a/components/bt/esp_ble_mesh/btc/btc_ble_mesh_prov.c
+++ b/components/bt/esp_ble_mesh/btc/btc_ble_mesh_prov.c
@@ -2026,8 +2026,8 @@ void btc_ble_mesh_model_call_handler(btc_msg_t *msg)
         break;
     }
     case BTC_BLE_MESH_ACT_SERVER_MODEL_SEND: {
-        /* arg->model_send.length contains opcode & message, 8 is used for TransMIC */
-        struct net_buf_simple *buf = bt_mesh_alloc_buf(arg->model_send.length + 8);
+        /* arg->model_send.length contains opcode & message, 4 is used for TransMIC */
+        struct net_buf_simple *buf = bt_mesh_alloc_buf(arg->model_send.length + 4);
         if (!buf) {
             BT_ERR("%s, Failed to allocate memory", __func__);
             break;
@@ -2044,8 +2044,8 @@ void btc_ble_mesh_model_call_handler(btc_msg_t *msg)
     }
     case BTC_BLE_MESH_ACT_CLIENT_MODEL_SEND: {
         bt_mesh_role_param_t common = {0};
-        /* arg->model_send.length contains opcode & message, 8 is used for TransMIC */
-        struct net_buf_simple *buf = bt_mesh_alloc_buf(arg->model_send.length + 8);
+        /* arg->model_send.length contains opcode & message, 4 is used for TransMIC */
+        struct net_buf_simple *buf = bt_mesh_alloc_buf(arg->model_send.length + 4);
         if (!buf) {
             BT_ERR("%s, Failed to allocate memory", __func__);
             break;