diff --git a/update-nix-path.sh b/update-nix-path.sh
new file mode 100755
index 0000000..0192629
--- /dev/null
+++ b/update-nix-path.sh
@@ -0,0 +1,38 @@
+#!/bin/sh
+
+# run this after a "sudo nixos-rebuild switch"
+# to update $NIX_PATH in this shell
+
+echo "NIX_PATH before:"; echo $NIX_PATH | tr ':' $'\n' | sed 's/^/  /'
+
+source /etc/set-environment
+
+echo "NIX_PATH after:"; echo $NIX_PATH | tr ':' $'\n' | sed 's/^/  /'
+
+exit 0
+
+
+
+related:
+
+https://discourse.nixos.org/t/where-is-nix-path-supposed-to-be-set/16434
+
+https://discourse.nixos.org/t/how-to-change-nix-path/4864
+
+/etc/nixos/flake.nix
+{
+  inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
+  outputs = { self, ... } @ inputs: {
+    nixosConfigurations.laptop1 = inputs.nixpkgs.lib.nixosSystem rec {
+      modules = [
+        ({ pkgs, ... }: {
+          nix.nixPath = [
+            "nixos=${inputs.nixpkgs}/nixos"
+            "nixpkgs=${inputs.nixpkgs}"
+          ];
+        })
+        ./configuration.nix
+      ];
+    };
+  };
+}