diff --git a/backup.nix b/backup.nix
index 7e95b6a..1accf0a 100644
--- a/backup.nix
+++ b/backup.nix
@@ -8,10 +8,13 @@ let
       pkgs.systemd
     ];
     text = ''
+      if [ "$#" -ne 1 ]; then
+        echo "Need exactly one argument, the path to backup.";
+        exit 1;
+      fi
       echo "Starting backup.";
-      path="$(systemd-escape -u --path ''${1})";
+      path="$(systemd-escape -u --path \"$1\")";
       restic backup "$path";
-      restic forget -d 7 -w 4 -m 6 --keep-within 1d --prune
     '';
   };
 in