diff --git a/pyproject.toml b/pyproject.toml
index 42bc6ee..de37ee9 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,5 +1,6 @@
 [build-system]
 requires = ["setuptools", "wheel"]
+build-backend = "setuptools.build_meta"
 
 [black]
 line_length = 120
diff --git a/setup.cfg b/setup.cfg
index 22f8dda..0f63744 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -24,7 +24,7 @@ sections = FUTURE,STDLIB,THIRDPARTY,FIRSTPARTY,LOCALFOLDER
 
 [metadata]
 name = shiv
-version = 0.5.2
+version = 1.0.0
 description = A command line utility for building fully self contained Python zipapps.
 long_description = file: README.md
 long_description_content_type = text/markdown
diff --git a/src/shiv/bootstrap/__init__.py b/src/shiv/bootstrap/__init__.py
index c36697b..8ba843e 100644
--- a/src/shiv/bootstrap/__init__.py
+++ b/src/shiv/bootstrap/__init__.py
@@ -1,12 +1,11 @@
 import compileall
+import hashlib
 import os
 import runpy
 import shutil
 import site
-
-import hashlib
-import sys
 import subprocess
+import sys
 import zipfile
 
 from contextlib import contextmanager, suppress
@@ -196,7 +195,11 @@ def bootstrap():  # pragma: no cover
         # determine if first run or forcing extract
         if not site_packages.exists() or env.force_extract:
             extract_site_packages(
-                archive, site_packages.parent, env.compile_pyc, env.compile_workers, env.force_extract,
+                archive,
+                site_packages.parent,
+                env.compile_pyc,
+                env.compile_workers,
+                env.force_extract,
             )
 
     # get sys.path's length
@@ -228,7 +231,7 @@ def bootstrap():  # pragma: no cover
 
         if preamble_bin.suffix == ".py":
             runpy.run_path(
-                preamble_bin.as_posix(),
+                str(preamble_bin),
                 init_globals={"archive": sys.argv[0], "env": env, "site_packages": site_packages},
                 run_name="__main__",
             )
diff --git a/src/shiv/bootstrap/interpreter.py b/src/shiv/bootstrap/interpreter.py
index 177be5e..3b59259 100644
--- a/src/shiv/bootstrap/interpreter.py
+++ b/src/shiv/bootstrap/interpreter.py
@@ -4,8 +4,8 @@
 It is used to enter an interactive interpreter session from an executable created with ``shiv``.
 """
 import code
-import sys
 import runpy
+import sys
 
 from pathlib import Path
 
diff --git a/src/shiv/builder.py b/src/shiv/builder.py
index 2a2195f..4523a07 100644
--- a/src/shiv/builder.py
+++ b/src/shiv/builder.py
@@ -126,7 +126,8 @@ def create_archive(
                     write_to_zipapp(archive, arcname, data, zipinfo_datetime, compression, stat=path.stat())
 
             if env.build_id is None:
-                # now that we have a hash of all the source files, use it as our build id
+                # Now that we have a hash of all the source files, use it as our build id if the user did not
+                # specify a custom one.
                 env.build_id = contents_hash.hexdigest()
 
             # now let's add the shiv bootstrap code.
diff --git a/src/shiv/cli.py b/src/shiv/cli.py
index 1053706..ba943ee 100644
--- a/src/shiv/cli.py
+++ b/src/shiv/cli.py
@@ -1,7 +1,6 @@
+import hashlib
 import os
 import shutil
-
-import hashlib
 import sys
 import time
 
@@ -17,13 +16,14 @@
 from .bootstrap.environment import Environment
 from .constants import (
     BUILD_AT_TIMESTAMP_FORMAT,
+    DEFAULT_SHEBANG,
     DISALLOWED_ARGS,
     DISALLOWED_PIP_ARGS,
     NO_ENTRY_POINT,
     NO_OUTFILE,
     NO_PIP_ARGS_OR_SITE_PACKAGES,
     SOURCE_DATE_EPOCH_DEFAULT,
-    SOURCE_DATE_EPOCH_ENV, DEFAULT_SHEBANG,
+    SOURCE_DATE_EPOCH_ENV,
 )
 
 __version__ = "1.0.0"
@@ -95,20 +95,39 @@ def copytree(src: Path, dst: Path) -> None:
 )
 @click.option("--console-script", "-c", default=None, help="The console_script to invoke.")
 @click.option("--output-file", "-o", help="The path to the output file for shiv to create.")
-@click.option("--python", "-p", help="The python interpreter to set as the shebang, a.k.a. whatever you want after '#!' (default is '/usr/bin/env python3')")
+@click.option(
+    "--python",
+    "-p",
+    help=(
+        "The python interpreter to set as the shebang, a.k.a. whatever you want after '#!' "
+        "(default is '/usr/bin/env python3')"
+    ),
+)
 @click.option(
     "--site-packages",
     help="The path to an existing site-packages directory to copy into the zipapp.",
     type=click.Path(exists=True),
     multiple=True,
 )
-@click.option("--build-id", help="Use a custom build id instead of an autogenerated one.", default=None)
+@click.option(
+    "--build-id",
+    default=None,
+    help=(
+        "Use a custom build id instead of the default (a SHA256 hash of the contents of the build). "
+        "Warning: must be unique per build!"
+    ),
+)
 @click.option("--compressed/--uncompressed", default=True, help="Whether or not to compress your zip.")
 @click.option(
-    "--compile-pyc", is_flag=True, help="Whether or not to compile pyc files during initial bootstrap.",
+    "--compile-pyc",
+    is_flag=True,
+    help="Whether or not to compile pyc files during initial bootstrap.",
 )
 @click.option(
-    "--extend-pythonpath", "-E", is_flag=True, help="Add the contents of the zipapp to PYTHONPATH (for subprocesses).",
+    "--extend-pythonpath",
+    "-E",
+    is_flag=True,
+    help="Add the contents of the zipapp to PYTHONPATH (for subprocesses).",
 )
 @click.option(
     "--reproducible",
@@ -171,6 +190,13 @@ def main(
             if supplied_arg in disallowed:
                 sys.exit(DISALLOWED_PIP_ARGS.format(arg=supplied_arg, reason=DISALLOWED_ARGS[disallowed]))
 
+    if build_id is not None:
+        click.secho(
+            "Warning! You have overridden the default build-id behavior, "
+            "executables created by shiv must have unique build IDs or unexpected behavior could occur.",
+            fg="yellow",
+        )
+
     sources: List[Path] = []
 
     with TemporaryDirectory() as tmp_site_packages:
diff --git a/src/shiv/constants.py b/src/shiv/constants.py
index 41ed393..6a7c7ca 100644
--- a/src/shiv/constants.py
+++ b/src/shiv/constants.py
@@ -27,5 +27,6 @@
 BUILD_AT_TIMESTAMP_FORMAT = "%Y-%m-%d %H:%M:%S"
 
 # The default shebang to use at the top of the pyz.
-# We use "/usr/bin/env" here because it's cross-platform compatible (https://docs.python.org/3/using/windows.html#shebang-lines)
+# We use "/usr/bin/env" here because it's cross-platform compatible
+# https://docs.python.org/3/using/windows.html#shebang-lines
 DEFAULT_SHEBANG = "/usr/bin/env python3"
diff --git a/test/test_cli.py b/test/test_cli.py
index b4ef064..df3fd11 100644
--- a/test/test_cli.py
+++ b/test/test_cli.py
@@ -11,7 +11,7 @@
 import pytest
 
 from click.testing import CliRunner
-from shiv.cli import get_interpreter_path, console_script_exists, find_entry_point, main
+from shiv.cli import console_script_exists, find_entry_point, main
 from shiv.constants import DISALLOWED_ARGS, DISALLOWED_PIP_ARGS, NO_OUTFILE, NO_PIP_ARGS_OR_SITE_PACKAGES
 from shiv.info import main as info_main
 from shiv.pip import install
@@ -86,21 +86,6 @@ def test_no_outfile(self, runner):
         assert result.exit_code == 1
         assert NO_OUTFILE in result.output
 
-    def test_find_interpreter(self):
-
-        interpreter = get_interpreter_path()
-
-        assert Path(interpreter).exists()
-        assert Path(interpreter).is_file()
-
-    def test_find_interpreter_false(self):
-
-        with mocked_sys_prefix():
-            interpreter = get_interpreter_path()
-
-        # should fall back on the current sys.executable
-        assert interpreter == sys.executable
-
     @pytest.mark.parametrize("arg", [arg for tup in DISALLOWED_ARGS.keys() for arg in tup])
     def test_disallowed_args(self, runner, arg):
         """This method tests that all the potential disallowed arguments match their error messages."""
diff --git a/tox.ini b/tox.ini
index bbdb0ab..3c05a74 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,4 +1,5 @@
 [tox]
+isolated_build = True
 envlist = py36, py37, py38, py39
 
 [gh-actions]