diff --git a/news/667.bugfix b/news/667.bugfix
new file mode 100644
index 000000000..668aae50d
--- /dev/null
+++ b/news/667.bugfix
@@ -0,0 +1,2 @@
+remove unecessary `default=[]` in IBaseClassMigratorForm
+[szakitibi]
\ No newline at end of file
diff --git a/plone/app/contenttypes/browser/migration.py b/plone/app/contenttypes/browser/migration.py
index 61354f405..357678786 100644
--- a/plone/app/contenttypes/browser/migration.py
+++ b/plone/app/contenttypes/browser/migration.py
@@ -44,7 +44,6 @@ class IBaseClassMigratorForm(Interface):
         value_type=schema.Choice(
             vocabulary="plone.app.contenttypes.migration.changed_base_classes",
         ),
-        default=[],
         required=True,
     )