diff --git a/src/ralph/lib/custom_fields/fields.py b/src/ralph/lib/custom_fields/fields.py
index c61c48bd65..fa59ffb672 100644
--- a/src/ralph/lib/custom_fields/fields.py
+++ b/src/ralph/lib/custom_fields/fields.py
@@ -3,7 +3,6 @@
 from functools import reduce
 from typing import Any
 
-from dataclasses import dataclass
 from django.contrib.contenttypes.fields import (
     create_generic_related_manager,
     GenericRelation
@@ -149,10 +148,10 @@ def values_list(self, *fields):
         )
 
 
-@dataclass
 class RelModel:
-    model: Any  # noqa
-    field: CustomFieldsWithInheritanceRelation  # noqa
+    def __init__(self, model: Any, field: CustomFieldsWithInheritanceRelation):
+        self.model = model
+        self.field = field
 
 
 class ReverseGenericRelatedObjectsWithInheritanceDescriptor: