diff --git a/flake.nix b/flake.nix
index a802b5c1..07dd59b5 100644
--- a/flake.nix
+++ b/flake.nix
@@ -57,6 +57,7 @@
             }: {
               nix = {
                 enable = true;
+                package = pkgs.nixVersions.nix_2_21;
                 settings = {
                   cores = 0;
                   max-jobs = "auto";