diff --git a/collatex-pythonport/collatex/core_functions.py b/collatex-pythonport/collatex/core_functions.py
index e6d4e1706..0bba53ce3 100644
--- a/collatex-pythonport/collatex/core_functions.py
+++ b/collatex-pythonport/collatex/core_functions.py
@@ -115,6 +115,8 @@ def export_alignment_table_as_xml(table):
     readings = []
     for column in table.columns:
         app = etree.Element('app')
+        if not column.variant:
+            app.set("type", "invariant")
         for key, value in sorted(column.tokens_per_witness.items()):
             child = etree.Element('rdg')
             child.attrib['wit'] = "#" + key