diff --git a/nixbld-etc-nixos/backup-module.nix b/nixbld-etc-nixos/backup-module.nix
index 4c32b510..36093f26 100644
--- a/nixbld-etc-nixos/backup-module.nix
+++ b/nixbld-etc-nixos/backup-module.nix
@@ -14,30 +14,23 @@ let
     "/var/lib/mattermost/data/2023*"
   ];
   makeBackup = pkgs.writeScript "make-backup" ''
-    #!${pkgs.bash}/bin/bash
+    #!${pkgs.bash}/bin/bash -p
 
     set -e
     umask 0077
 
-    FILENAME=backup-`date +%F`.tar.bz2.gpg
-
     DBDUMPDIR=`mktemp -d`
-    pushd $DBDUMPDIR
+    trap "rm -rf $DBDUMPDIR" EXIT
+    cd $DBDUMPDIR
 
     ${config.services.mysql.package}/bin/mysqldump --user=root --single-transaction flarum > flarum.sql
-    ${pkgs.sudo}/bin/sudo -u mattermost ${config.services.postgresql.package}/bin/pg_dump mattermost > mattermost.sql
-    ${pkgs.sudo}/bin/sudo -u rt ${config.services.postgresql.package}/bin/pg_dump rt5 > rt.sql
+    ${config.services.postgresql.package}/bin/pg_dump mattermost > mattermost.sql
+    ${config.services.postgresql.package}/bin/pg_dump rt5 > rt.sql
 
+    exec 6< /etc/nixos/secret/backup-passphrase
     ${pkgs.gnutar}/bin/tar cf - ${lib.concatMapStringsSep " " (p: "--exclude \"${p}\"") excludePaths} /etc/nixos /var/vmail /var/lib/hedgedoc /var/lib/gitea /var/lib/afws /var/lib/mattermost/data /var/www/193thz flarum.sql mattermost.sql rt.sql | \
         ${pkgs.bzip2}/bin/bzip2 | \
-        ${pkgs.gnupg}/bin/gpg --symmetric --batch --passphrase-file /etc/nixos/secret/backup-passphrase > /home/backupdl/$FILENAME
-
-    popd
-    rm -rf $DBDUMPDIR
-
-    chown backupdl.users /home/backupdl/$FILENAME
-
-    echo Backup done
+        ${pkgs.gnupg}/bin/gpg --symmetric --batch --passphrase-fd 6
   '';
   cfg = config.services.mlabs-backup;
 in
@@ -51,20 +44,20 @@ in
   };
 
   config = mkIf cfg.enable {
-    systemd.services.mlabs-backup = {
-      description = "M-Labs backup";
-      serviceConfig = {
-        Type = "oneshot";
-        User = "root";
-        Group = "root";
-        ExecStart = "${makeBackup}";
-      };
+    users.extraGroups.backupdl = { };
+    users.extraUsers.backupdl = {
+      isNormalUser = true;
+      extraGroups = ["backupdl" "nextcloud"];
+      openssh.authorizedKeys.keys = [
+        "ssh-rsa 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 backupdl@minipc"
+      ];
     };
-
-    systemd.timers.mlabs-backup = {
-      description = "M-Labs backup";
-      wantedBy = [ "timers.target" ];
-      timerConfig.OnCalendar = "tuesday,friday *-*-* 08:00:00";
+    security.wrappers.mlabs-backup = {
+      source = makeBackup;
+      setuid = true;
+      owner = "root";
+      group = "backupdl";
+      permissions = "g+x";
     };
   };
 }
diff --git a/nixbld-etc-nixos/configuration.nix b/nixbld-etc-nixos/configuration.nix
index ac285589..35457a50 100644
--- a/nixbld-etc-nixos/configuration.nix
+++ b/nixbld-etc-nixos/configuration.nix
@@ -527,13 +527,6 @@ in
       "ssh-rsa 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"
     ];
   };
-  users.extraUsers.backupdl = {
-    isNormalUser = true;
-    extraGroups = ["nextcloud"];
-    openssh.authorizedKeys.keys = [
-      "ssh-rsa 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 backupdl@minipc"
-    ];
-  };
   users.extraUsers.occheung = {
     isNormalUser = true;
     openssh.authorizedKeys.keys = [