diff --git a/artiq/tools.py b/artiq/tools.py
index 9296e8253..619fab412 100644
--- a/artiq/tools.py
+++ b/artiq/tools.py
@@ -2,6 +2,7 @@ from operator import itemgetter
 import importlib.machinery
 import linecache
 import logging
+import sys
 import os.path