diff --git a/zipline/lib/labelarray.py b/zipline/lib/labelarray.py
index 96a2a4fc..d6cc979a 100644
--- a/zipline/lib/labelarray.py
+++ b/zipline/lib/labelarray.py
@@ -10,6 +10,7 @@ from numpy import ndarray
 import pandas as pd
 from toolz import compose
 
+from zipline.utils.compat import unicode
 from zipline.utils.preprocess import preprocess
 from zipline.utils.sentinel import sentinel
 from zipline.utils.input_validation import (