diff --git a/drivers/rptun/rptun.c b/drivers/rptun/rptun.c
index 0a75c2e9ee5..ea1c21af993 100644
--- a/drivers/rptun/rptun.c
+++ b/drivers/rptun/rptun.c
@@ -441,8 +441,8 @@ static int rptun_dev_start(FAR struct remoteproc *rproc)
       rsc->rpmsg_vring1.da = da1;
 
       shbuf   = (FAR char *)rsc + tbsz + v0sz + v1sz;
-      shbufsz = rsc->buf_size *
-                (rsc->rpmsg_vring0.num + rsc->rpmsg_vring1.num);
+      shbufsz = rsc->config.txbuf_size * rsc->rpmsg_vring0.num +
+                rsc->config.rxbuf_size * rsc->rpmsg_vring1.num;
 
       rpmsg_virtio_init_shm_pool(&priv->shm_pool, shbuf, shbufsz);
 
diff --git a/include/nuttx/rptun/rptun.h b/include/nuttx/rptun/rptun.h
index 194ba801703..6eb277410d6 100644
--- a/include/nuttx/rptun/rptun.h
+++ b/include/nuttx/rptun/rptun.h
@@ -260,7 +260,7 @@ struct __attribute__((aligned(B2C(8)))) rptun_rsc_s
   struct fw_rsc_vdev       rpmsg_vdev;
   struct fw_rsc_vdev_vring rpmsg_vring0;
   struct fw_rsc_vdev_vring rpmsg_vring1;
-  unsigned int             buf_size;
+  struct fw_rsc_config     config;
 };
 
 struct rptun_dev_s;