diff --git a/nixos/modules/rename.nix b/nixos/modules/rename.nix
index b15dd84999a9..26b20f5eb0df 100644
--- a/nixos/modules/rename.nix
+++ b/nixos/modules/rename.nix
@@ -197,6 +197,12 @@ with lib;
     (mkRenamedOptionModule [ "fonts" "fontconfig" "ultimate" "forceAutohint" ] [ "fonts" "fontconfig" "forceAutohint" ])
     (mkRenamedOptionModule [ "fonts" "fontconfig" "ultimate" "renderMonoTTFAsBitmap" ] [ "fonts" "fontconfig" "renderMonoTTFAsBitmap" ])
 
+    # postgresqlBackup
+    (mkRemovedOptionModule [ "services" "postgresqlBackup" "period" ] ''
+       A systemd timer is now used instead of cron.
+       The starting time can be configured via <literal>services.postgresqlBackup.startAt</literal>.
+    '')
+
     # Profile splitting
     (mkRenamedOptionModule [ "virtualization" "growPartition" ] [ "boot" "growPartition" ])
 
diff --git a/nixos/modules/services/backup/postgresql-backup.nix b/nixos/modules/services/backup/postgresql-backup.nix
index 93dcd2f96479..2ec78ce6f2cf 100644
--- a/nixos/modules/services/backup/postgresql-backup.nix
+++ b/nixos/modules/services/backup/postgresql-backup.nix
@@ -34,7 +34,7 @@ let
         User = "postgres";
       };
 
-      startAt = cfg.period;
+      startAt = cfg.startAt;
     };
 
 in {
@@ -50,10 +50,10 @@ in {
         '';
       };
 
-      period = mkOption {
+      startAt = mkOption {
         default = "*-*-* 01:15:00";
         description = ''
-          This option defines (in the format used by <literal>systemd.time</literal>) when the
+          This option defines (see <literal>systemd.time</literal> for format) when the
           databases should be dumped.
           The default is to update at 01:15 (at night) every day.
         '';