diff --git a/README.md b/README.md
index 494b78c..db381d3 100644
--- a/README.md
+++ b/README.md
@@ -107,10 +107,10 @@ In `/etc/nixos/configuration.nix`:
 { pkgs, ... }: {
   environment.systemPackages = with pkgs; [ direnv nix-direnv ];
   # nix options for derivations to persist garbage collection
-  nix.extraOptions = ''
-    keep-outputs = true
-    keep-derivations = true
-  '';
+  nix.settings = {
+    keep-outputs = true;
+    keep-derivations = true;
+  }
   environment.pathsToLink = [
     "/share/nix-direnv"
   ];