diff --git a/tox.ini b/pyproject.toml
similarity index 72%
rename from tox.ini
rename to pyproject.toml
index 8c9d6390..c2ab75e6 100644
--- a/tox.ini
+++ b/pyproject.toml
@@ -1,3 +1,12 @@
+# https://snarky.ca/what-the-heck-is-pyproject-toml/
+[build-system]
+requires = ["setuptools", "wheel"]
+build-backend = "setuptools.build_meta"
+
+# Need to use legacy format for the time being
+# https://tox.readthedocs.io/en/3.20.0/example/basic.html#pyproject-toml-tox-legacy-ini
+[tool.tox]
+legacy_tox_ini = """
 [tox]
 envlist = py35,py36,py37,py38
 
@@ -22,3 +31,5 @@ commands =
     flake8 telethon/ telethon_generator/ tests/ --count --select=E9,F63,F7,F82 --show-source --statistics
     # exit-zero treats all errors as warnings. The GitHub editor is 127 chars wide
     flake8 telethon/ telethon_generator/ tests/ --count --exit-zero --exclude telethon/tl/,telethon/errors/rpcerrorlist.py --max-complexity=10 --max-line-length=127 --statistics
+
+"""
diff --git a/setup.py b/setup.py
index b03fe95c..3446369d 100755
--- a/setup.py
+++ b/setup.py
@@ -15,12 +15,14 @@ import json
 import os
 import re
 import shutil
+import sys
 from pathlib import Path
 from subprocess import run
-from sys import argv
 
 from setuptools import find_packages, setup
 
+# Needed since we're importing local files
+sys.path.insert(0, os.path.dirname(__file__))
 
 class TempWorkDir:
     """Switches the working directory to be the one on which this file lives,
@@ -148,7 +150,7 @@ def generate(which, action='gen'):
         )
 
 
-def main():
+def main(argv):
     if len(argv) >= 2 and argv[1] in ('gen', 'clean'):
         generate(argv[2:], argv[1])
 
@@ -231,4 +233,4 @@ def main():
 
 if __name__ == '__main__':
     with TempWorkDir():
-        main()
+        main(sys.argv)