diff --git a/src/caosadvancedtools/models/data_model.py b/src/caosadvancedtools/models/data_model.py
index 360cfcefd8744af0d081d9a9049aa8364b83816d..fc82a9370e50353624d9d8f9069502c54257fff6 100644
--- a/src/caosadvancedtools/models/data_model.py
+++ b/src/caosadvancedtools/models/data_model.py
@@ -71,7 +71,7 @@ class DataModel(dict):
     def append(self, entity: db.Entity):
         self[entity.name] = entity
 
-    def extend(self, entities: list[db.Entity]):
+    def extend(self, entities: List[db.Entity]):
         for entity in entities:
             self.append(entity)