diff --git a/units/user-.slice.d/10-defaults.conf b/units/user-.slice.d/10-defaults.conf
index f1d118562c7..c81a00e0502 100644
--- a/units/user-.slice.d/10-defaults.conf
+++ b/units/user-.slice.d/10-defaults.conf
@@ -11,6 +11,7 @@
 Description=User Slice of UID %j
 Documentation=man:user@.service(5)
 After=systemd-user-sessions.service
+StopWhenUnneeded=yes
 
 [Slice]
 TasksMax=33%