--- a/hw/virtio-serial-bus.c
+++ b/hw/virtio-serial-bus.c
@@ -429,6 +429,10 @@ static int virtio_serial_load(QEMUFile *f, void *opaque, int version_id)
         id = qemu_get_be32(f);
         port = find_port_by_id(s, id);

+        if (port == NULL) {
+            return -EINVAL;
+        }
+
         port->guest_connected = qemu_get_byte(f);
     }