diff --git a/src/ifcopenshell-python/ifcopenshell/api/classification/add_classification.py b/src/ifcopenshell-python/ifcopenshell/api/classification/add_classification.py
index ee72bd7585..d0e18d265e 100644
--- a/src/ifcopenshell-python/ifcopenshell/api/classification/add_classification.py
+++ b/src/ifcopenshell-python/ifcopenshell/api/classification/add_classification.py
@@ -110,7 +110,9 @@ class Usecase:
                 "IfcCalendarDate", **ifcopenshell.util.date.datetime2ifc(edition_date, "IfcCalendarDate")
             )
         else:
-            result.EditionDate = ifcopenshell.util.date.datetime2ifc(edition_date, "IfcDate")
+            if edition_date:
+                edition_date = ifcopenshell.util.date.datetime2ifc(edition_date, "IfcDate")
+            result.EditionDate = edition_date
 
         self.relate_to_project(result)