diff --git a/core/elasticsearch/documents.py b/core/elasticsearch/documents.py
index a59c8b3a..ee48d0b2 100644
--- a/core/elasticsearch/documents.py
+++ b/core/elasticsearch/documents.py
@@ -126,6 +126,7 @@ class TestModelDocument(Document):
             "title",
         ]
         ignore_signals = True
+        related_models: list = []
 
 
 registry.register_document(TestModelDocument)