diff --git a/units/systemd-nspawn@.service.in b/units/systemd-nspawn@.service.in
index 3e26b53fd..5e8612113 100644
--- a/units/systemd-nspawn@.service.in
+++ b/units/systemd-nspawn@.service.in
@@ -17,6 +17,7 @@ KillMode=mixed
 Type=notify
 RestartForceExitStatus=133
 SuccessExitStatus=133
+Slice=machine.slice
 Delegate=yes
 
 [Install]