diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1dc34ad70..78ed86fcd 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,7 @@
 
 - Removed export of `Pipfile.lock` to `requirements.txt` during the build. ([#1593](https://github.com/heroku/heroku-buildpack-python/pull/1593))
 - Removed internal `pipenv-to-pip` script that was unintentionally exposed onto `PATH`. ([#1593](https://github.com/heroku/heroku-buildpack-python/pull/1593))
+- Stopped exposing the internal `BIN_DIR`, `EXPORT_PATH` and `PROFILE_PATH` environment variables to `bin/{pre,post}_compile` and other subprocesses. ([#1595](https://github.com/heroku/heroku-buildpack-python/pull/1595)).
 
 ## [v251] - 2024-06-07
 
diff --git a/bin/compile b/bin/compile
index 051aa87f4..5ffb15e05 100755
--- a/bin/compile
+++ b/bin/compile
@@ -1,18 +1,7 @@
 #!/usr/bin/env bash
+# Usage: bin/compile <build-dir> <cache-dir> <env-dir>
+# See: https://devcenter.heroku.com/articles/buildpack-api
 
-# The Heroku Python Buildpack. This script accepts parameters for a build
-# directory, a cache directory, and a directory for app environment variables.
-
-# Warning: there are a few hacks in this script to accommodate excellent builds
-# on Heroku. No guarantee for external compatibility is made. However,
-# everything should work fine outside of the Heroku environment, if the
-# environment is setup correctly.
-
-# Usage:
-#
-#     $ bin/compile <build-dir> <cache-dir> <env-path>
-
-# Fail fast and fail hard.
 set -eo pipefail
 
 # Used by buildpack-stdlib's metrics features.
@@ -21,18 +10,20 @@ export BUILDPACK_LOG_FILE=${BUILDPACK_LOG_FILE:-/dev/null}
 
 [ "$BUILDPACK_XTRACE" ] && set -o xtrace
 
+BUILD_DIR="${1}"
+CACHE_DIR="${2}"
+ENV_DIR="${3}"
+
+# The absolute path to the root of the buildpack.
+BUILDPACK_DIR=$(cd "$(dirname "$(dirname "${BASH_SOURCE[0]}")")" && pwd)
+
+source "${BUILDPACK_DIR}/bin/utils"
+
 # Prepend proper path for old-school virtualenv hackery.
-# This may not be neccessary.
+# This may not be necessary.
 export PATH=:/usr/local/bin:$PATH
 
-# Setup Path variables, for later use in the Buildpack.
-BIN_DIR=$(cd "$(dirname "$0")"; pwd) # absolute path
-ROOT_DIR=$(dirname "$BIN_DIR")
-BUILD_DIR=$1
-CACHE_DIR=$2
-ENV_DIR=$3
-
-# Export Path variables, for use in sub-scripts.
+# Exported for use in subshells, such as the steps run via sub_env.
 export BUILD_DIR CACHE_DIR ENV_DIR
 
 # Set the base URL for downloading buildpack assets like Python runtimes.
@@ -43,8 +34,7 @@ S3_BASE_URL="${BUILDPACK_S3_BASE_URL:-"https://heroku-buildpack-python.s3.us-eas
 # This has to be exported since it's used by the geo-libs step which is run in a subshell.
 
 # Default Python Versions
-# shellcheck source=bin/default_pythons
-source "$BIN_DIR/default_pythons"
+source "${BUILDPACK_DIR}/bin/default_pythons"
 
 # Common Problem Warnings:
 # This section creates a temporary file in which to stick the output of `pip install`.
@@ -53,19 +43,14 @@ source "$BIN_DIR/default_pythons"
 WARNINGS_LOG=$(mktemp)
 
 # Sanitize externally-provided environment variables:
-# The following environment variables are either problematic or simply unneccessary
+# The following environment variables are either problematic or simply unnecessary
 # for the buildpack to have knowledge of, so we unset them, to keep the environment
 # as clean and pristine as possible.
 unset PYTHONHOME PYTHONPATH
 
-# Import the utils script, which contains helper functions used throughout the buildpack.
-# shellcheck source=bin/utils
-source "$BIN_DIR/utils"
-
 # Import the warnings script, which contains the `pip install` user warning mechanisms
 # (mentioned and explained above)
-# shellcheck source=bin/warnings
-source "$BIN_DIR/warnings"
+source "${BUILDPACK_DIR}/bin/warnings"
 
 # Make the directory in which we will create symlinks from the temporary build directory
 # to `/app`.
@@ -73,22 +58,11 @@ source "$BIN_DIR/warnings"
 # More on this topic later.
 mkdir -p /app/.heroku
 
-# This buildpack programatically generates (or simply copies) a number of files for
-# buildpack machinery: an export script, and a number of `.profile.d` scripts. This
-# section declares the locations of those files and targets.
 PROFILE_PATH="$BUILD_DIR/.profile.d/python.sh"
-EXPORT_PATH="$BIN_DIR/../export"
+EXPORT_PATH="${BUILDPACK_DIR}/bin/../export"
 GUNICORN_PROFILE_PATH="$BUILD_DIR/.profile.d/python.gunicorn.sh"
 WEB_CONCURRENCY_PROFILE_PATH="$BUILD_DIR/.profile.d/WEB_CONCURRENCY.sh"
 
-# We'll need to send these statics to other scripts we `source`.
-export BUILD_DIR CACHE_DIR BIN_DIR PROFILE_PATH EXPORT_PATH
-
-# Python Environment Variables
-# Set Python-specific environment variables, for running Python within the buildpack.
-# Notes on each variable included.
-
-# PATH is relatively obvious, we need to be able to execute 'python'.
 export PATH=/app/.heroku/python/bin:/app/.heroku/vendor/bin:$PATH
 # Tell Python to not buffer it's stdin/stdout.
 export PYTHONUNBUFFERED=1
@@ -108,10 +82,6 @@ export PKG_CONFIG_PATH=/app/.heroku/vendor/lib/pkg-config:/app/.heroku/python/li
 # Disable pip's warnings about EOL Python since we show our own.
 export PIP_NO_PYTHON_VERSION_WARNING=1
 
-# The Application Code
-# --------------------
-
-# Switch to the repo's context.
 cd "$BUILD_DIR"
 
 # The Cache
@@ -146,13 +116,10 @@ fi
 # This part of the code is used to allow users to customize their build experience
 # without forking the buildpack by providing a `bin/pre_compile` script, which gets
 # run inline with the buildpack automatically.
-
-# shellcheck source=bin/steps/hooks/pre_compile
-source "$BIN_DIR/steps/hooks/pre_compile"
+source "${BUILDPACK_DIR}/bin/steps/hooks/pre_compile"
 
 # Sticky runtimes. If there was a previous build, and it used a given version of Python,
-# continue to use that version of Python in perpituity (warnings will be raised if
-# they are out–of–date).
+# continue to use that version of Python in perpetuity.
 if [ -f "$CACHE_DIR/.heroku/python-version" ]; then
   CACHED_PYTHON_VERSION=$(cat "$CACHE_DIR/.heroku/python-version")
 fi
@@ -167,9 +134,7 @@ fi
 # Pipenv Python version support.
 # Detect the version of Python requested from a Pipfile (e.g. python_version or python_full_version).
 # Convert it to a runtime.txt file.
-
-# shellcheck source=bin/steps/pipenv-python-version
-source "$BIN_DIR/steps/pipenv-python-version"
+source "${BUILDPACK_DIR}/bin/steps/pipenv-python-version"
 
 if [[ -f runtime.txt ]]; then
   # PYTHON_VERSION_SOURCE may have already been set by the pipenv-python-version step.
@@ -195,7 +160,7 @@ mkdir -p "$(dirname "$PROFILE_PATH")"
 mkdir -p /app/.heroku/src
 
 # On Heroku CI, builds happen in `/app`. Otherwise, on the Heroku platform,
-# they occur in a temp directory. Beacuse Python is not portable, we must create
+# they occur in a temp directory. Because Python is not portable, we must create
 # symlinks to emulate that we are operating in `/app` during the build process.
 # This is (hopefully obviously) because apps end up running from `/app` in production.
 # Realpath is used to support use-cases where one of the locations is a symlink to the other.
@@ -210,13 +175,11 @@ fi
 # Download / Install Python, from pre-build binaries available on Amazon S3.
 # This step also bootstraps pip / setuptools.
 (( start=$(nowms) ))
-# shellcheck source=bin/steps/python
-source "$BIN_DIR/steps/python"
+source "${BUILDPACK_DIR}/bin/steps/python"
 mtime "python.install.time" "${start}"
 
 # Install Pipenv dependencies, if a Pipfile was provided.
-# shellcheck source=bin/steps/pipenv
-source "$BIN_DIR/steps/pipenv"
+source "${BUILDPACK_DIR}/bin/steps/pipenv"
 
 # If no requirements.txt file given, assume `setup.py develop` is intended.
 # This allows for people to ship a setup.py application to Heroku
@@ -229,8 +192,7 @@ fi
 # This sets up and installs sqlite3 dev headers and the sqlite3 binary but not the
 # libsqlite3-0 library since that exists on the stack image.
 (( start=$(nowms) ))
-# shellcheck source=bin/steps/sqlite3
-source "$BIN_DIR/steps/sqlite3"
+source "${BUILDPACK_DIR}/bin/steps/sqlite3"
 buildpack_sqlite3_install
 mtime "sqlite3.install.time" "${start}"
 
@@ -239,13 +201,12 @@ mtime "sqlite3.install.time" "${start}"
 
 # Install dependencies with pip (where the magic happens).
 (( start=$(nowms) ))
-# shellcheck source=bin/steps/pip-install
-source "$BIN_DIR/steps/pip-install"
+source "${BUILDPACK_DIR}/bin/steps/pip-install"
 mtime "pip.install.time" "${start}"
 
 # Support for NLTK corpora.
 (( start=$(nowms) ))
-sub_env "$BIN_DIR/steps/nltk"
+sub_env "${BUILDPACK_DIR}/bin/steps/nltk"
 mtime "nltk.download.time" "${start}"
 
 # Support for editable installations. Here, we are copying pip–created src directory,
@@ -264,11 +225,11 @@ fi
 # These failures are intentional — if collectstatic (which can be tricky, at times) fails,
 # your build fails.
 (( start=$(nowms) ))
-sub_env "$BIN_DIR/steps/collectstatic"
+sub_env "${BUILDPACK_DIR}/bin/steps/collectstatic"
 mtime "collectstatic.time" "${start}"
 
 
-# Progamatically create .profile.d script for application runtime environment variables.
+# Programmatically create .profile.d script for application runtime environment variables.
 
 # Set the PATH to include Python / pip / pipenv / etc.
 set_env PATH "\$HOME/.heroku/python/bin:\$PATH"
@@ -306,12 +267,11 @@ EOT
 fi
 
 # Install sane-default script for $WEB_CONCURRENCY and $FORWARDED_ALLOW_IPS.
-cp "$ROOT_DIR/vendor/WEB_CONCURRENCY.sh" "$WEB_CONCURRENCY_PROFILE_PATH"
-cp "$ROOT_DIR/vendor/python.gunicorn.sh" "$GUNICORN_PROFILE_PATH"
+cp "${BUILDPACK_DIR}/vendor/WEB_CONCURRENCY.sh" "$WEB_CONCURRENCY_PROFILE_PATH"
+cp "${BUILDPACK_DIR}/vendor/python.gunicorn.sh" "$GUNICORN_PROFILE_PATH"
 
 # Experimental post_compile hook. Don't remove this.
-# shellcheck source=bin/steps/hooks/post_compile
-source "$BIN_DIR/steps/hooks/post_compile"
+source "${BUILDPACK_DIR}/bin/steps/hooks/post_compile"
 
 # Store new artifacts in the cache.
 rm -rf "$CACHE_DIR/.heroku/python"
diff --git a/bin/detect b/bin/detect
index eeb965b0f..118248a6c 100755
--- a/bin/detect
+++ b/bin/detect
@@ -1,16 +1,6 @@
 #!/usr/bin/env bash
-
-# This script serves as the
-# [**Python Buildpack**](https://github.com/heroku/heroku-buildpack-python)
-# detector.
-#
-# A [buildpack](https://devcenter.heroku.com/articles/buildpacks) is an
-# adapter between a Python application and Heroku's runtime.
-
-# ## Usage
-# Compiling an app into a slug is simple:
-#
-#     $ bin/detect <build-dir> <cache-dir>
+# Usage: bin/compile <build-dir>
+# See: https://devcenter.heroku.com/articles/buildpack-api
 
 BUILD_DIR=$1
 
diff --git a/bin/release b/bin/release
index 9454913ca..282d26e44 100755
--- a/bin/release
+++ b/bin/release
@@ -1,9 +1,12 @@
 #!/usr/bin/env bash
-# bin/release <build-dir>
+# Usage: bin/release <build-dir>
+# See: https://devcenter.heroku.com/articles/buildpack-api
 
 set -euo pipefail
 
-BUILD_DIR=$1
+BUILD_DIR="${1}"
+
+# The absolute path to the root of the buildpack.
 BUILDPACK_DIR=$(cd "$(dirname "$(dirname "${BASH_SOURCE[0]}")")" && pwd)
 
 # Unfortunately the build system doesn't source the `export` script before
@@ -16,7 +19,6 @@ set +u
 source "${BUILDPACK_DIR}/export"
 set -u
 
-# shellcheck source=bin/utils
 source "${BUILDPACK_DIR}/bin/utils"
 
 if [[ -f "${BUILD_DIR}/manage.py" ]] && is_module_available 'django' && is_module_available 'psycopg2'; then
diff --git a/bin/steps/collectstatic b/bin/steps/collectstatic
index e5ea756d1..3f43adaa7 100755
--- a/bin/steps/collectstatic
+++ b/bin/steps/collectstatic
@@ -10,8 +10,9 @@
 #   - $DISABLE_COLLECTSTATIC: disables this functionality.
 #   - $DEBUG_COLLECTSTATIC: upon failure, print out environment variables.
 
-# shellcheck source=bin/utils
-source "$BIN_DIR/utils"
+# This script is run in a subshell via sub_env so doesn't inherit the vars/utils from `bin/compile`.
+BUILDPACK_DIR=$(cd "$(dirname "$(dirname "$(dirname "${BASH_SOURCE[0]}")")")" && pwd)
+source "${BUILDPACK_DIR}/bin/utils"
 
 if [[ -f .heroku/collectstatic_disabled ]]; then
   puts-step "Skipping Django collectstatic since the file '.heroku/collectstatic_disabled' exists."
diff --git a/bin/steps/nltk b/bin/steps/nltk
index 86f53cab2..27571ce61 100755
--- a/bin/steps/nltk
+++ b/bin/steps/nltk
@@ -9,9 +9,9 @@
 #
 # This script is invoked by [`bin/compile`](/).
 
-# Syntax sugar.
-# shellcheck source=bin/utils
-source "$BIN_DIR/utils"
+# This script is run in a subshell via sub_env so doesn't inherit the vars/utils from `bin/compile`.
+BUILDPACK_DIR=$(cd "$(dirname "$(dirname "$(dirname "${BASH_SOURCE[0]}")")")" && pwd)
+source "${BUILDPACK_DIR}/bin/utils"
 
 # Check that nltk was installed by pip, otherwise obviously not needed
 if is_module_available 'nltk'; then
diff --git a/bin/steps/pip-install b/bin/steps/pip-install
index 65e338c84..40707ab8e 100755
--- a/bin/steps/pip-install
+++ b/bin/steps/pip-install
@@ -1,11 +1,7 @@
 #!/usr/bin/env bash
 
-# shellcheck source=bin/utils
-source "$BIN_DIR/utils"
-
 if [ ! "$SKIP_PIP_INSTALL" ]; then
 
-    # Install dependencies with Pip.
     puts-step "Installing requirements with pip"
 
     # Set Pip env vars
diff --git a/bin/steps/pipenv b/bin/steps/pipenv
index dbcbc97c1..056657c0d 100755
--- a/bin/steps/pipenv
+++ b/bin/steps/pipenv
@@ -2,9 +2,6 @@
 
 # export CLINT_FORCE_COLOR=1
 # export PIPENV_FORCE_COLOR=1
-# shellcheck source=bin/utils
-source "$BIN_DIR/utils"
-set -e
 
 # Previous versions of the buildpack used to cache the checksum of the lockfile to allow
 # for skipping pipenv install if the lockfile was unchanged. However, this is not always safe
diff --git a/bin/steps/sqlite3 b/bin/steps/sqlite3
index 7aeb6bbfe..d22455fde 100755
--- a/bin/steps/sqlite3
+++ b/bin/steps/sqlite3
@@ -3,9 +3,6 @@
 # TODO: Remove this entirely since the Python stdlib now includes modern sqlite support,
 # and the APT buildpack should be used if an app needs the sqlite CLI/headers.
 
-# shellcheck source=bin/utils
-source "$BIN_DIR/utils"
-
 sqlite3_install() {
   HEROKU_PYTHON_DIR="$1"
   HEADERS_ONLY="$3"
diff --git a/bin/test-compile b/bin/test-compile
index fa4a6580a..03fd6fadb 100755
--- a/bin/test-compile
+++ b/bin/test-compile
@@ -1,13 +1,14 @@
 #!/usr/bin/env bash
+# Usage: bin/test-compile <build-dir> <cache-dir> <env-dir>
+# See: https://devcenter.heroku.com/articles/testpack-api
 
-# Syntax sugar.
-BIN_DIR=$(cd "$(dirname "$0")" || return; pwd) # absolute path
+set -euo pipefail
 
-# shellcheck source=bin/utils
-source "$BIN_DIR/utils"
+# The absolute path to the root of the buildpack.
+BUILDPACK_DIR=$(cd "$(dirname "$(dirname "${BASH_SOURCE[0]}")")" && pwd)
 
 # Locale support for Pipenv.
 export LC_ALL=C.UTF-8
 export LANG=C.UTF-8
 
-DISABLE_COLLECTSTATIC=1 INSTALL_TEST=1 "$(dirname "${0:-}")/compile" "$1" "$2" "$3"
\ No newline at end of file
+DISABLE_COLLECTSTATIC=1 INSTALL_TEST=1 "${BUILDPACK_DIR}/bin/compile" "${1}" "${2}" "${3}"
diff --git a/bin/utils b/bin/utils
index 467cde6d5..3d44fd54b 100755
--- a/bin/utils
+++ b/bin/utils
@@ -1,14 +1,11 @@
 #!/usr/bin/env bash
+
+# Be careful about moving these to bin/compile, since this utils script is sourced
+# directly by other scripts run via subshells, and not only from bin/compile.
 shopt -s extglob
 shopt -s nullglob
 
-# This is necessary since this script is sometimes sourced from
-# subshells that don't have the variables from bin/compile.
-# Remove this once we no longer wrap all the things in `sub_env`.
-BIN_DIR=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
-ROOT_DIR=$(dirname "${BIN_DIR}")
-# shellcheck source=vendor/buildpack-stdlib_v8.sh
-source "${ROOT_DIR}/vendor/buildpack-stdlib_v8.sh"
+source "${BUILDPACK_DIR}/vendor/buildpack-stdlib_v8.sh"
 
 if [ "$(uname)" == Darwin ]; then
     sed() { command sed -l "$@"; }
@@ -71,7 +68,7 @@ is_module_available() {
 get_requirement_version() {
   local package_name="${1}"
   local requirement
-  requirement=$(cat "${ROOT_DIR}/requirements/${package_name}.txt")
+  requirement=$(cat "${BUILDPACK_DIR}/requirements/${package_name}.txt")
   local requirement_version="${requirement#"${package_name}=="}"
   echo "${requirement_version}"
 }
diff --git a/bin/warnings b/bin/warnings
index 5e714122d..7a67835bc 100755
--- a/bin/warnings
+++ b/bin/warnings
@@ -1,5 +1,4 @@
 #!/usr/bin/env bash
-shopt -s extglob
 
 gdal-missing() {
   if grep -qi 'Could not find gdal-config' "$WARNINGS_LOG"; then
diff --git a/spec/hatchet/hooks_spec.rb b/spec/hatchet/hooks_spec.rb
index bb15c8ded..bf2d243b1 100644
--- a/spec/hatchet/hooks_spec.rb
+++ b/spec/hatchet/hooks_spec.rb
@@ -9,7 +9,6 @@
     it 'runs the hooks with the correct environment' do
       expected_env_vars = %w[
         _
-        BIN_DIR
         BPLOG_PREFIX
         BUILD_DIR
         BUILDPACK_LOG_FILE
@@ -18,7 +17,6 @@
         CPLUS_INCLUDE_PATH
         DYNO
         ENV_DIR
-        EXPORT_PATH
         HOME
         LANG
         LD_LIBRARY_PATH
@@ -27,7 +25,6 @@
         PATH
         PIP_NO_PYTHON_VERSION_WARNING
         PKG_CONFIG_PATH
-        PROFILE_PATH
         PWD
         PYTHONUNBUFFERED
         REQUEST_ID