diff --git a/units/systemd-nspawn@.service.in b/units/systemd-nspawn@.service.in
index 1927c4d4853..ea28941507d 100644
--- a/units/systemd-nspawn@.service.in
+++ b/units/systemd-nspawn@.service.in
@@ -13,7 +13,7 @@ Before=machines.target
 After=network.target
 
 [Service]
-ExecStart=@bindir@/systemd-nspawn --quiet --keep-unit --boot --link-journal=try-guest --network-veth --settings=override --machine=%i
+ExecStart=@bindir@/systemd-nspawn --quiet --keep-unit --boot --link-journal=try-guest --network-veth -U --settings=override --machine=%i
 KillMode=mixed
 Type=notify
 RestartForceExitStatus=133