diff --git a/quic/qbone/bonnet/tun_device.cc b/quic/qbone/bonnet/tun_device.cc
index 6c0a8a5..e266654 100644
--- a/quic/qbone/bonnet/tun_device.cc
+++ b/quic/qbone/bonnet/tun_device.cc
@@ -30,7 +30,9 @@
       kernel_(*kernel) {}
 
 TunDevice::~TunDevice() {
-  Down();
+  if (!persist_) {
+    Down();
+  }
   CleanUpFileDescriptor();
 }