diff --git a/Library/Homebrew/style.rb b/Library/Homebrew/style.rb
index 6beacb720b..544249a26b 100644
--- a/Library/Homebrew/style.rb
+++ b/Library/Homebrew/style.rb
@@ -263,6 +263,7 @@ module Homebrew
         HOMEBREW_REPOSITORY/"completions/bash/brew",
         HOMEBREW_REPOSITORY/"Dockerfile",
         *HOMEBREW_REPOSITORY.glob(".devcontainer/**/*.sh"),
+        *HOMEBREW_REPOSITORY.glob("package/scripts/*"),
         *HOMEBREW_LIBRARY.glob("Homebrew/**/*.sh").reject { |path| path.to_s.include?("/vendor/") },
         *HOMEBREW_LIBRARY.glob("Homebrew/shims/**/*").map(&:realpath).uniq
                          .reject(&:directory?)
diff --git a/package/scripts/postinstall b/package/scripts/postinstall
index c0cfffc7b0..7ea0389bb5 100755
--- a/package/scripts/postinstall
+++ b/package/scripts/postinstall
@@ -1,42 +1,54 @@
 #!/bin/bash
+# $1 Full path to the installer - unused
+# $2 Location of the temporary brew install we're moving into place
+# $3 Target install location - unused
+# $4 System root directory - unused
 set -e
 
 # verify the files exist
 tmp_brew="$2"
-if [[ ! -d "${tmp_brew:?}" ]]; then
-    echo "no directory at $tmp_brew, exiting"
-    exit 1
+if [[ ! -d "${tmp_brew:?}" ]]
+then
+  echo "no directory at ${tmp_brew}, exiting"
+  exit 1
 fi
 
 # pick the correct target
-if [[ $(uname -m) == "x86_64" ]];then
+if [[ $(uname -m) == "x86_64" ]]
+then
   target="/usr/local"
 else
   target="/opt/Homebrew"
 fi
 
 loggedInUser=$(echo "show State:/Users/ConsoleUser" | scutil | awk '/Name :/ { print $3 }')
-if [[ -f "$target/bin/brew" ]]; then
-    if [[ $(sudo -u"$loggedInUser" "$target/bin/brew" developer) =~ "enabled" ]]; then
-      echo "developer install, exiting"
-      exit 0
-    fi
-    if [[ $("$tmp_brew/bin/brew" --version | head -n1) != $("$target/bin/brew" --version | head -n1) ]]; then
-      echo "already an outdated install at $target, updating"
-      sudo -u"$loggedInUser" "$target/bin/brew" update --auto-update
-    else
-      echo "already an up-to-date install at $target, exiting"
-    fi
+if [[ -f "${target}/bin/brew" ]]
+then
+  if [[ $(sudo -u"${loggedInUser}" git -C "${target}" branch --show-current) != "master" ]]
+  then
+    echo "working on brew modifications, exiting"
+    rm -rf "${tmp_brew:?}/*"
     exit 0
+  fi
+  if [[ $("${tmp_brew}/bin/brew" --version | head -n1) != $("${target}/bin/brew" --version | head -n1) ]]
+  then
+    echo "already an outdated install at ${target}, updating"
+    sudo -u"${loggedInUser}" "${target}/bin/brew" update --auto-update
+  else
+    echo "already an up-to-date install at ${target}, exiting"
+  fi
+
+  rm -rf "${tmp_brew:?}/*"
+  exit 0
 fi
 
-group=$(id -gn "$loggedInUser")
+group=$(id -gn "${loggedInUser}")
 
-install -d -o "$loggedInUser" -g "$group" "$target"
-cp -RX "$tmp_brew/" "$target"
+install -d -o "${loggedInUser}" -g "${group}" "${target}"
+cp -RX "${tmp_brew}/" "${target}"
 
 # set permissions
-chown -R "$loggedInUser:$group" "$target/*"
+chown -R "${loggedInUser}:${group}" "${target}/*"
 
 # cleanup
 rm -rf "${tmp_brew:?}/*"
diff --git a/package/scripts/preinstall b/package/scripts/preinstall
index 03bbcac607..49afc85251 100755
--- a/package/scripts/preinstall
+++ b/package/scripts/preinstall
@@ -1,16 +1,32 @@
 #!/bin/bash
 
 # Checked for installed CLT
-if [[ -e "/Library/Developer/CommandLineTools/usr/bin/git" ]]; then
+if [[ -e "/Library/Developer/CommandLineTools/usr/bin/git" ]]
+then
   exit 0
 fi
 
-if [[ -z "$COMMAND_LINE_INSTALL" ]]; then
-  printf "No auto-install of CommandLine Tools in headless install!"
-  exit 1
-fi
+CLT_PLACEHOLDER="/tmp/.com.apple.dt.CommandLineTools.installondemand.in-progress"
+touch "${CLT_PLACEHOLDER}"
 
-if ! /usr/bin/xcode-select --install; then
-  printf "Failed to install CommandLine Tools!"
-  exit 1
+CLT_PACKAGE=$(softwareupdate -l |
+  grep -B 1 "Command Line Tools" |
+  awk -F"*" '/^ *\*/ {print $2}' |
+  sed -e 's/^ *Label: //' -e 's/^ *//' |
+  sort -V |
+  tail -n1)
+softwareupdate -i "${CLT_PACKAGE}"
+rm -f "${CLT_PLACEHOLDER}"
+if ! [[ -f "/Library/Developer/CommandLineTools/usr/bin/git" ]]
+then
+  if [[ -z "${COMMAND_LINE_INSTALL}" ]]
+  then
+    echo
+    printf "Requesting user install of Xcode Command Line Tools:"
+    /usr/bin/xcode-select --install
+  else
+    echo
+    printf "Run 'xcode-select --install' to install the Xcode Command Line Tools before running a headless brew install."
+    exit 1
+  fi
 fi