diff --git a/nix/buildkit-update.sh b/nix/buildkit-update.sh
new file mode 100755
index 00000000..6b5a43c6
--- /dev/null
+++ b/nix/buildkit-update.sh
@@ -0,0 +1,35 @@
+#!/usr/bin/env bash
+{ # https://stackoverflow.com/a/21100710
+
+  ## Re-generate the buildkit.nix file - with the current 'master' branch.
+
+  set -e
+
+  if [ ! -f "nix/buildkit.nix" ]; then
+    echo >&2 "Must run in project root"
+    exit 1
+  fi
+
+  now=$( date -u '+%Y-%m-%d %H:%M %Z' )
+  commit=$( git ls-remote https://github.com/civicrm/civicrm-buildkit.git | awk '/refs\/heads\/master$/ { print $1 }' )
+  url="https://github.com/civicrm/civicrm-buildkit/archive/${commit}.tar.gz"
+  hash=$( nix-prefetch-url "$url" --type sha256 --unpack )
+
+  function render_file() {
+    echo "{ pkgs ? import <nixpkgs> {} }:"
+    echo ""
+    echo "## Get civicrm-buildkit from github."
+    echo "## Based on \"master\" branch circa $now"
+    echo "import (pkgs.fetchzip {"
+    echo "  url = \"$url\";"
+    echo "  sha256 = \"$hash\";"
+    echo "})"
+    echo
+    echo "## Get a local copy of civicrm-buildkit. (Useful for developing patches.)"
+    echo "# import ((builtins.getEnv \"HOME\") + \"/buildkit/default.nix\")"
+    echo "# import ((builtins.getEnv \"HOME\") + \"/bknix/default.nix\")"
+  }
+  render_file > nix/buildkit.nix
+
+  exit
+}
diff --git a/nix/buildkit.nix b/nix/buildkit.nix
new file mode 100644
index 00000000..e9f3d6f4
--- /dev/null
+++ b/nix/buildkit.nix
@@ -0,0 +1,12 @@
+{ pkgs ? import <nixpkgs> {} }:
+
+## Get civicrm-buildkit from github.
+## Based on "master" branch circa 2023-08-22 10:32 UTC
+import (pkgs.fetchzip {
+  url = "https://github.com/civicrm/civicrm-buildkit/archive/04b338a52bbf0bdc21edafe564b875138c1db12c.tar.gz";
+  sha256 = "1r6m830lyv6xf0yxz392izhwlnbahhc7s4r71riyqryzkr6psfyd";
+})
+
+## Get a local copy of civicrm-buildkit. (Useful for developing patches.)
+# import ((builtins.getEnv "HOME") + "/buildkit/default.nix")
+# import ((builtins.getEnv "HOME") + "/bknix/default.nix")
diff --git a/shell.nix b/shell.nix
index d7fa37c3..65068719 100644
--- a/shell.nix
+++ b/shell.nix
@@ -8,15 +8,7 @@
 
 let
 
-  buildkit = import (pkgs.fetchFromGitHub {
-    owner = "totten";
-    repo = "civicrm-buildkit";
-    rev = "153371e9bdcb22392b878cca545df0888fb61925";
-    sha256 = "sha256-rdwmA4uqIqfqXu2f+ewVH0Gs/BzcB13p8oRbbTdUsAs=";
-  });
-
-  ## If you're trying to patch buildkit at the sametime, then use a local copy:
-  #buildkit = import ((builtins.getEnv "HOME") + "/bknix/default.nix");
+  buildkit = (import ./nix/buildkit.nix) { inherit pkgs; };
 
 in