diff --git a/nw/core/tree.py b/nw/core/tree.py
index c150c8e5..ac3ab45c 100644
--- a/nw/core/tree.py
+++ b/nw/core/tree.py
@@ -26,7 +26,6 @@
 """
 
 import logging
-import json
 import os
 
 from lxml import etree