diff --git a/python/presto/Pgplot.py b/python/presto/Pgplot.py
index 7299b1b5e..9becae374 100644
--- a/python/presto/Pgplot.py
+++ b/python/presto/Pgplot.py
@@ -16,6 +16,7 @@
 from __future__ import print_function
 from builtins import range
 from builtins import object
+import sys
 import numpy as Num
 from presto import ppgplot