diff --git a/tools/emacs-pkgs/nix-util/default.nix b/tools/emacs-pkgs/nix-util/default.nix
index ffeb1cefa..b167cb964 100644
--- a/tools/emacs-pkgs/nix-util/default.nix
+++ b/tools/emacs-pkgs/nix-util/default.nix
@@ -4,4 +4,5 @@ depot.tools.emacs-pkgs.buildEmacsPackage {
   pname = "nix-util";
   version = "1.0";
   src = ./nix-util.el;
+  externalRequires = epkgs: [ epkgs.s ];
 }
diff --git a/tools/emacs-pkgs/nix-util/nix-util.el b/tools/emacs-pkgs/nix-util/nix-util.el
index 855b53a74..924a65880 100644
--- a/tools/emacs-pkgs/nix-util/nix-util.el
+++ b/tools/emacs-pkgs/nix-util/nix-util.el
@@ -1,18 +1,21 @@
 ;;; nix-util.el --- Utilities for dealing with Nix code. -*- lexical-binding: t; -*-
 ;;
 ;; Copyright (C) 2019 Google Inc.
+;; Copyright (C) 2022 The TVL Authors
 ;;
 ;; Author: Vincent Ambo <tazjin@google.com>
 ;; Version: 1.0
-;; Package-Requires: (json map)
+;; Package-Requires: (cl json map s)
 ;;
 ;;; Commentary:
 ;;
 ;; This package adds some functionality that I find useful when
 ;; working in Nix buffers or programs installed from Nix.
 
+(require 'cl)
 (require 'json)
 (require 'map)
+(require 's)
 
 (defvar nix-depot-path "/home/tazjin/depot")