diff --git a/odml/tools/xmlparser.py b/odml/tools/xmlparser.py
index 790528c1..f4ea3a46 100644
--- a/odml/tools/xmlparser.py
+++ b/odml/tools/xmlparser.py
@@ -82,6 +82,7 @@ def save_element(e):
 
             if isinstance(val, list):
                 for v in val:
+                    if v is None: continue
                     ele = XMLWriter.save_element(v)
                     cur.append(ele)
             else: