diff --git a/gramps/gui/editors/test/test_editreference.py b/gramps/gui/editors/test/test_editreference.py
index 06d5322a1..d711849b7 100644
--- a/gramps/gui/editors/test/test_editreference.py
+++ b/gramps/gui/editors/test/test_editreference.py
@@ -22,6 +22,7 @@
 
 import unittest
 import sys
+import os
 try:
     if sys.version_info < (3,3):
         from mock import Mock, patch