diff --git a/certbot-dns-dnsimple/setup.py b/certbot-dns-dnsimple/setup.py
index e02c79110..9088e8113 100644
--- a/certbot-dns-dnsimple/setup.py
+++ b/certbot-dns-dnsimple/setup.py
@@ -1,3 +1,4 @@
+import os
 from setuptools import setup
 from setuptools import find_packages