diff --git a/tiingo/api.py b/tiingo/api.py
index 3f3bbaa..7e986b2 100644
--- a/tiingo/api.py
+++ b/tiingo/api.py
@@ -3,7 +3,7 @@
 import os
 import pkg_resources
 import csv
-from StringIO import StringIO
+from io import StringIO
 from zipfile import ZipFile