diff --git a/tools/xen/build_domU.sh b/tools/xen/build_domU.sh
index 455ad26..a0fd316 100755
--- a/tools/xen/build_domU.sh
+++ b/tools/xen/build_domU.sh
@@ -182,7 +182,7 @@
 if [ -z $PUB_BR ]; then
     PUB_BR=$(xe network-list --minimal uuid=$PUB_NET params=bridge)
 fi
-$TOP_DIR/scripts/install-os-vpx.sh -f $XVA -v $VM_BR -m $MGT_BR -p $PUB_BR -l $GUEST_NAME -w
+$TOP_DIR/scripts/install-os-vpx.sh -f $XVA -v $VM_BR -m $MGT_BR -p $PUB_BR -l $GUEST_NAME -w -k "flat_network_bridge=${VM_BR}"
 
 # If we have copied our ssh credentials, use ssh to monitor while the installation runs
 WAIT_TILL_LAUNCH=${WAIT_TILL_LAUNCH:-1}