diff --git a/home/NixOs.nix b/home/NixOs.nix
index 2c63fe9..b7382d0 100644
--- a/home/NixOs.nix
+++ b/home/NixOs.nix
@@ -47,7 +47,9 @@ in
         }
       ) { } cfg.users;
 
-      backupFileExtension = "old";
+      backupFileExtension =
+        "backup-"
+        + pkgs.lib.readFile "${pkgs.runCommand "timestamp" { } "echo -n date '+%Y%m%d%H%M%S' > $out"}";
     };
   };
 }