diff --git a/hw/char/virtio-serial-bus.c b/hw/char/virtio-serial-bus.c
index 016aba6..2094d21 100644
--- a/hw/char/virtio-serial-bus.c
+++ b/hw/char/virtio-serial-bus.c
@@ -985,8 +985,7 @@
         return;
     }
 
-    port->bh = qemu_bh_new_guarded(flush_queued_data_bh, port,
-                                   &dev->mem_reentrancy_guard);
+    port->bh = virtio_bh_new_guarded(dev, flush_queued_data_bh, port);
     port->elem = NULL;
 }