diff --git a/mitogen/su.py b/mitogen/su.py
index 9faee2d4..5f52e08b 100644
--- a/mitogen/su.py
+++ b/mitogen/su.py
@@ -27,7 +27,6 @@
 # POSSIBILITY OF SUCH DAMAGE.
 
 import logging
-import os
 
 import mitogen.core
 import mitogen.parent