diff --git a/evaluate.py b/evaluate.py
index 435a6be8..01385039 100755
--- a/evaluate.py
+++ b/evaluate.py
@@ -4,6 +4,7 @@ from __future__ import absolute_import, division, print_function
 
 import itertools
 import json
+import sys
 
 from multiprocessing import cpu_count