diff --git a/Admin/cronjob/self_update b/Admin/cronjob/self_update
--- a/Admin/cronjob/self_update
+++ b/Admin/cronjob/self_update
@@ -1,20 +1,20 @@
 #!/bin/bash
 #
 # self-update of the administrative isabelle repository
 #
 # Need to copy this file manually to $HOME/cronjob in order to
 # avoid overwriting the running self_update by itself!
 
 source "$HOME/.bashrc"
 
 cd "$HOME/cronjob"
 mkdir -p run log
 
-{
+(
   export LANG=C
   export HGPLAIN=
 
   "${HG:-hg}" -R isabelle pull "https://isabelle.sketis.net/repos/isabelle" || echo "self_update pull failed" >&2
   "${HG:-hg}" -R isabelle update -C || echo "self_update update failed" >&2
   isabelle/bin/isabelle components -a 2>&1 || echo "self_update components failed" >&2
-} > run/self_update.out
+) > run/self_update.out