diff --git a/nixbld-etc-nixos/backup-module.nix b/nixbld-etc-nixos/backup-module.nix
index 2804c8d1..61bf2708 100644
--- a/nixbld-etc-nixos/backup-module.nix
+++ b/nixbld-etc-nixos/backup-module.nix
@@ -51,7 +51,7 @@ in
     systemd.timers.mlabs-backup = {
       description = "M-Labs backup";
       wantedBy = [ "timers.target" ];
-      timerConfig.OnCalendar = "weekly";
+      timerConfig.OnCalendar = "tuesday,friday";
     };
   };
 }