diff --git a/artiq-fast/default.nix b/artiq-fast/default.nix
index 5246f93..638baa0 100644
--- a/artiq-fast/default.nix
+++ b/artiq-fast/default.nix
@@ -1,8 +1,4 @@
-{ pkgs ? import <nixpkgs> {
-  overlays = [ (self: super: {
-    python3 = super.python3.overrideAttrs(oa: { configureFlags = oa.configureFlags ++ ["--enable-optimizations" "--with-lto"]; });
-  }) ];
-}}:
+{ pkgs ? import <nixpkgs> {}}:
 with pkgs;
 let
   pythonDeps = import ./pkgs/python-deps.nix { inherit (pkgs) stdenv fetchFromGitHub python3Packages; };