diff --git a/README b/README
index a2a49b1..38e0f52 100644
--- a/README
+++ b/README
@@ -12,6 +12,12 @@ mount /dev/disk/by-label/boot /mnt/boot
 nixos-generate-config --root /mnt
 # copy configuration to /mnt/etc/nixos
 nix-env -iA nixos.git
+# work around https://github.com/NixOS/nixpkgs/issues/209819
+rm /etc/nix/nix.conf
+cp /etc/static/nix/nix.conf /etc/nix/nix.conf
+vi /etc/nix/nix.conf
+# set: substituters = https://cache.nixos.org/ https://nixbld.m-labs.hk/
+# set: trusted-public-keys = cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY= nixbld.m-labs.hk-1:5aSRVA5b320xbNvu30tqxVPXpld73bhtOeH6uAjRyHc=
 nixos-install --no-root-password --flake /mnt/etc/nixos#artiq
 reboot
 # run memtest86