diff --git a/biscuit/apps/untis/api.py b/biscuit/apps/untis/api.py
index d903d5dd6923a95bbf3152f2955ae343123e7dd3..b0fc5bb7e90b8d7f7460d72aa46338acefe7fb5b 100755
--- a/biscuit/apps/untis/api.py
+++ b/biscuit/apps/untis/api.py
@@ -154,6 +154,8 @@ def format_classes(classes):
     """
     classes_as_dict = {}
 
+    classes = sorted(classes, key=lambda class_: class_.name)
+
     for _class in classes:
         step = _class.name[:-1]
         part = _class.name[-1:]