diff --git a/backup.nix b/backup.nix
index c8efb3f..641f0f6 100644
--- a/backup.nix
+++ b/backup.nix
@@ -57,7 +57,7 @@ in
       };
       serviceConfig = {
         Type = "oneshot";
-        ExecStart = "${restic-wrapper}/bin/restic-wrapper %I";
+        ExecStart = "${restic-wrapper}/bin/restic-wrapper %f";
       };
     };
     systemd.timers."backup-helper@" = {