diff --git a/siso.py b/siso.py
index 2ae18dc1f..f6cf01365 100644
--- a/siso.py
+++ b/siso.py
@@ -9,6 +9,7 @@ binary when run inside a gclient source tree, so users can just type
 
 import os
 import signal
+import shutil
 import subprocess
 import sys