diff --git a/odmantic/model.py b/odmantic/model.py
index 08308f29..397689a9 100644
--- a/odmantic/model.py
+++ b/odmantic/model.py
@@ -941,7 +941,7 @@ class Model(_BaseODMModel, metaclass=ModelMetaclass):
         __collection__: ClassVar[str] = ""
         __primary_field__: ClassVar[str] = ""
 
-        id: Union[ObjectId, Any] = Field()  # TODO fix basic id field typing
+        id: Union[ObjectId, Any] = Field(default_factory=ObjectId)
 
     def __setattr__(self, name: str, value: Any) -> None:
         if name == self.__primary_field__: