diff -r f33942053466 -r c2cba67145eb xmlclass/xsdschema.py
--- a/xmlclass/xsdschema.py	Tue Oct 10 12:21:46 2017 +0300
+++ b/xmlclass/xsdschema.py	Tue Oct 10 12:34:50 2017 +0300
@@ -152,7 +152,7 @@
 
     for child in children:
         if child["type"] == SIMPLETYPE:
-            union["memberTypes"].appendchild
+            union["memberTypes"].append(child)
     if len(union["memberTypes"]) == 0:
         raise ValueError("No base type has been defined for union!")
     return union