diff --git a/python/plugins/processing/gui/ProcessingToolbox.py b/python/plugins/processing/gui/ProcessingToolbox.py
index 5bef7e6893e..18d1298ff39 100755
--- a/python/plugins/processing/gui/ProcessingToolbox.py
+++ b/python/plugins/processing/gui/ProcessingToolbox.py
@@ -27,6 +27,7 @@ __copyright__ = '(C) 2012, Victor Olaya'
 
 __revision__ = '$Format:%H$'
 
+import operator
 import os
 
 from qgis.PyQt import uic