diff --git a/setup.py b/setup.py
index 8b18362c1..8758e3dc2 100755
--- a/setup.py
+++ b/setup.py
@@ -1,5 +1,7 @@
 #!/usr/bin/env python
 
+import os
+
 from setuptools import find_packages, setup
 import fastentrypoints   # Monkey-patches setuptools.