diff --git a/search_engine_image_thumbnail/models/se_image_field_thumbnail_size.py b/search_engine_image_thumbnail/models/se_image_field_thumbnail_size.py
index 1a23ef4e..44140a85 100644
--- a/search_engine_image_thumbnail/models/se_image_field_thumbnail_size.py
+++ b/search_engine_image_thumbnail/models/se_image_field_thumbnail_size.py
@@ -107,7 +107,7 @@ def _compute_field_id_domain(self):
             for field in domain_fields:
                 if self._is_field_valid_for_thumbnail(field):
                     names.append(field.name)
-            record.field_id_domain = json.dumps(
+            record.field_id_domain = (
                 [("name", "in", names), ("model_id", "=", record.model_id.id)]
                 if names
                 else FALSE_DOMAIN