diff --git a/setup.py b/setup.py
new file mode 100644
index 0000000000..7b44ded04a
--- /dev/null
+++ b/setup.py
@@ -0,0 +1,31 @@
+import sys
+
+from setuptools import setup
+
+sys.stderr.write(
+    """
+===============================
+Unsupported installation method
+===============================
+httpx no longer supports installation with `python setup.py install`.
+Please use `python -m pip install .` instead.
+"""
+)
+sys.exit(1)
+
+
+# The below code will never execute, however GitHub is particularly
+# picky about where it finds Python packaging metadata.
+# See: https://github.com/github/feedback/discussions/6456
+#
+# To be removed once GitHub catches up.
+
+setup(
+    name="httpx",
+    install_requires=[
+        "certifi",
+        "sniffio",
+        "rfc3986[idna2008]>=1.3,<2",
+        "httpcore>=0.15.0,<0.16.0",
+    ],
+)