diff --git a/backup.nix b/backup.nix
index 12c1476..72b4087 100644
--- a/backup.nix
+++ b/backup.nix
@@ -35,7 +35,7 @@ in
     };
     password-file = lib.mkOption {
       type = lib.types.str;
-      defaullt = null;
+      default = null;
       description = "File containing the restic password.";
     };
     randomized-delay = lib.mkOption {