diff --git a/README.md b/README.md
index 7deeba1..90e2e46 100644
--- a/README.md
+++ b/README.md
@@ -17,9 +17,9 @@ pip install pydantic-mongo
 ```python
 from bson import ObjectId
 from pydantic import BaseModel
-from pydantic_mongo import AbstractRepository, ObjectIdField
+from pydantic_mongo import AbstractRepository, PydanticObjectId
 from pymongo import MongoClient
-from typing import List
+from typing import Optional, List
 import os
 
 class Foo(BaseModel):
@@ -31,7 +31,8 @@ class Bar(BaseModel):
    banana: str = 'y'
 
 class Spam(BaseModel):
-   id: ObjectIdField = None
+   # PydanticObjectId is an alias to Annotated[ObjectId, ObjectIdAnnotation]
+   id: Optional[PydanticObjectId] = None
    foo: Foo
    bars: List[Bar]
 
@@ -64,7 +65,7 @@ spam_repository.delete(spam)
 # Find One By Id
 result = spam_repository.find_one_by_id(spam.id)
 
-# Find One By Id using string if the id attribute is a ObjectIdField
+# Find One By Id using string if the id attribute is a PydanticObjectId
 result = spam_repository.find_one_by_id(ObjectId('611827f2878b88b49ebb69fc'))
 assert result.foo.count == 2
 
diff --git a/integration_test/test_readme.py b/integration_test/test_readme.py
index 94c64e5..703e0e0 100644
--- a/integration_test/test_readme.py
+++ b/integration_test/test_readme.py
@@ -3,6 +3,7 @@
 import os
 import re
 
+
 def extract_python_snippets(content):
     # Regular expression pattern for finding Python code blocks
     pattern = r'```python(.*?)```'
diff --git a/mypy.ini b/mypy.ini
new file mode 100644
index 0000000..895701c
--- /dev/null
+++ b/mypy.ini
@@ -0,0 +1,2 @@
+[mypy]
+plugins = pydantic.mypy
\ No newline at end of file
diff --git a/phulpyfile.py b/phulpyfile.py
index a9df97a..d0fc7fa 100644
--- a/phulpyfile.py
+++ b/phulpyfile.py
@@ -46,8 +46,6 @@ def integration_test(phulpy):
 
 @task
 def typecheck(phulpy):
-    result = system(
-        r'find ./pydantic_mongo -name "*.py" -exec mypy --ignore-missing-imports --follow-imports=skip --strict-optional {} \+'
-    )
+    result = system('mypy pydantic_mongo test --check-untyped-defs')
     if result:
         raise Exception("lint test failed")
diff --git a/pydantic_mongo/__init__.py b/pydantic_mongo/__init__.py
index 26bfd07..83bfe65 100644
--- a/pydantic_mongo/__init__.py
+++ b/pydantic_mongo/__init__.py
@@ -1,5 +1,10 @@
 from .abstract_repository import AbstractRepository
-from .fields import ObjectIdField
+from .fields import ObjectIdAnnotation, ObjectIdField, PydanticObjectId
 from .version import __version__  # noqa: F401
 
-__all__ = ["ObjectIdField", "AbstractRepository"]
+__all__ = [
+    "AbstractRepository",
+    "ObjectIdField",
+    "ObjectIdAnnotation",
+    "PydanticObjectId",
+]
diff --git a/pydantic_mongo/abstract_repository.py b/pydantic_mongo/abstract_repository.py
index 0c4a4eb..112f961 100644
--- a/pydantic_mongo/abstract_repository.py
+++ b/pydantic_mongo/abstract_repository.py
@@ -9,6 +9,7 @@
     Type,
     TypeVar,
     Union,
+    cast,
 )
 
 from pydantic import BaseModel
@@ -26,10 +27,13 @@
 
 T = TypeVar("T", bound=BaseModel)
 OutputT = TypeVar("OutputT", bound=BaseModel)
-
 Sort = Sequence[Tuple[str, int]]
 
 
+class ModelWithId(BaseModel):
+    id: Any
+
+
 class AbstractRepository(Generic[T]):
     class Meta:
         collection_name: str
@@ -53,8 +57,6 @@ def get_collection(self) -> Collection:
         return self.__database[self.__collection_name]
 
     def __validate(self):
-        if not issubclass(self.__document_class, BaseModel):
-            raise Exception("Document class should inherit BaseModel")
         if "id" not in self.__document_class.model_fields:
             raise Exception("Document class should have id field")
         if not self.__collection_name:
@@ -67,10 +69,11 @@ def to_document(model: T) -> dict:
         :param model:
         :return: dict
         """
-        data = model.model_dump()
+        model_with_id = cast(ModelWithId, model)
+        data = model_with_id.model_dump()
         data.pop("id")
-        if model.id:
-            data["_id"] = model.id
+        if model_with_id.id:
+            data["_id"] = model_with_id.id
         return data
 
     def __map_id(self, data: dict) -> dict:
@@ -109,15 +112,16 @@ def save(self, model: T) -> Union[InsertOneResult, UpdateResult]:
         Save entity to database. It will update the entity if it has id, otherwise it will insert it.
         """
         document = self.to_document(model)
+        model_with_id = cast(ModelWithId, model)
 
-        if model.id:
+        if model_with_id.id:
             mongo_id = document.pop("_id")
             return self.get_collection().update_one(
                 {"_id": mongo_id}, {"$set": document}, upsert=True
             )
 
         result = self.get_collection().insert_one(document)
-        model.id = result.inserted_id
+        model_with_id.id = result.inserted_id
         return result
 
     def save_many(self, models: Iterable[T]):
@@ -128,7 +132,8 @@ def save_many(self, models: Iterable[T]):
         models_to_update = []
 
         for model in models:
-            if model.id:
+            model_with_id = cast(ModelWithId, model)
+            if model_with_id.id:
                 models_to_update.append(model)
             else:
                 models_to_insert.append(model)
@@ -138,7 +143,7 @@ def save_many(self, models: Iterable[T]):
             )
 
             for idx, inserted_id in enumerate(result.inserted_ids):
-                models_to_insert[idx].id = inserted_id
+                cast(ModelWithId, models_to_insert[idx]).id = inserted_id
 
         if len(models_to_update) == 0:
             return
@@ -152,7 +157,7 @@ def save_many(self, models: Iterable[T]):
         self.get_collection().bulk_write(bulk_operations)
 
     def delete(self, model: T):
-        return self.get_collection().delete_one({"_id": model.id})
+        return self.get_collection().delete_one({"_id": cast(ModelWithId, model).id})
 
     def delete_by_id(self, _id: Any):
         return self.get_collection().delete_one({"_id": _id})
@@ -198,7 +203,7 @@ def find_by_with_output_type(
             cursor.limit(limit)
         if skip:
             cursor.skip(skip)
-        if sort:
+        if mapped_sort:
             cursor.sort(mapped_sort)
         return map(lambda doc: self.to_model_custom(output_type, doc), cursor)
 
@@ -285,7 +290,7 @@ def paginate_with_output_type(
         )
 
         return map(
-            lambda model: Edge[T](
+            lambda model: Edge[OutputT](
                 node=model,
                 cursor=encode_pagination_cursor(
                     get_pagination_cursor_payload(model, sort_keys)
diff --git a/pydantic_mongo/fields.py b/pydantic_mongo/fields.py
index 3e6ef2c..2d4b171 100644
--- a/pydantic_mongo/fields.py
+++ b/pydantic_mongo/fields.py
@@ -2,9 +2,10 @@
 
 from bson import ObjectId
 from pydantic_core import core_schema
+from typing_extensions import Annotated
 
 
-class ObjectIdField(ObjectId):
+class ObjectIdAnnotation:
     @classmethod
     def __get_pydantic_core_schema__(
         cls, _source_type: Any, _handler: Any
@@ -31,3 +32,13 @@ def validate(cls, value):
             raise ValueError("Invalid id")
 
         return ObjectId(value)
+
+
+# Deprecated, use PydanticObjectId instead.
+class ObjectIdField(ObjectId):
+    @classmethod
+    def __get_pydantic_core_schema__(cls, _source_type: Any, _handler: Any):
+        return ObjectIdAnnotation.__get_pydantic_core_schema__(_source_type, _handler)
+
+
+PydanticObjectId = Annotated[ObjectId, ObjectIdAnnotation]
diff --git a/pydantic_mongo/pagination.py b/pydantic_mongo/pagination.py
index 5d66752..fc243fb 100644
--- a/pydantic_mongo/pagination.py
+++ b/pydantic_mongo/pagination.py
@@ -16,7 +16,7 @@ class Edge(BaseModel, Generic[DataT]):
 
 
 def encode_pagination_cursor(data: List) -> str:
-    byte_data = bson.BSON.encode({"v": data})
+    byte_data: bytes = bson.BSON.encode({"v": data})
     byte_data = zlib.compress(byte_data, 9)
     return b64encode(byte_data).decode("utf-8")
 
diff --git a/requirements_test.txt b/requirements_test.txt
index ad30968..b369ae6 100644
--- a/requirements_test.txt
+++ b/requirements_test.txt
@@ -7,7 +7,7 @@ pytest==8.1.1
 pytest-cov==4.1.0
 pytest-mock==3.12.0
 mongomock==4.1.2
-pydantic>=2.0.2
+pydantic==2.7.1
 pymongo==4.6.3
 mypy==1.10.0
 mypy-extensions==1.0.0
diff --git a/test/test_enhance_meta.py b/test/test_enhance_meta.py
index a993cfd..221e2a1 100644
--- a/test/test_enhance_meta.py
+++ b/test/test_enhance_meta.py
@@ -1,11 +1,11 @@
 import pytest
 from pydantic import BaseModel, Field
-
-from pydantic_mongo import AbstractRepository, ObjectIdField
+from pydantic_mongo import AbstractRepository, PydanticObjectId
+from typing_extensions import Optional
 
 
 class HamModel(BaseModel):
-    id: ObjectIdField = Field(default=None)
+    id: Optional[PydanticObjectId]
     name: str
 
 
@@ -31,7 +31,7 @@ def test_repository_with_v2_meta(ham_repo):
 
 
 def test_save_with_new_repo(clean_ham_collection, ham_repo):
-    m = HamModel(name="wilfred")
+    m = HamModel(id=None, name="wilfred")
     assert m.id is None, "should have no id"
     ham_repo.save(m)
     assert m.id
diff --git a/test/test_fields.py b/test/test_fields.py
index 6a7043e..6ff156d 100644
--- a/test/test_fields.py
+++ b/test/test_fields.py
@@ -1,4 +1,5 @@
 import pytest
+from typing import Optional
 from bson import ObjectId
 from pydantic import BaseModel, ValidationError
 
@@ -6,7 +7,7 @@
 
 
 class User(BaseModel):
-    id: ObjectIdField = None
+    id: ObjectIdField
 
 
 class TestFields:
@@ -26,5 +27,6 @@ def test_modify_schema(self):
         assert {
             "title": "User",
             "type": "object",
-            "properties": {"id": {"default": None, "title": "Id", "type": "string"}},
+            "properties": {"id": {"title": "Id", "type": "string"}},
+            "required": ["id"],
         } == schema
diff --git a/test/test_pagination.py b/test/test_pagination.py
index e539f04..6ace3ce 100644
--- a/test/test_pagination.py
+++ b/test/test_pagination.py
@@ -1,5 +1,4 @@
-import datetime
-from typing import List
+from typing import List, Optional
 
 from bson import ObjectId
 from pydantic import BaseModel
@@ -13,7 +12,7 @@
 
 class Foo(BaseModel):
     count: int
-    size: float = None
+    size: Optional[float] = None
 
 
 class Bar(BaseModel):
@@ -22,7 +21,7 @@ class Bar(BaseModel):
 
 
 class Spam(BaseModel):
-    id: str = None
+    id: Optional[str] = None
     foo: Foo
     bars: List[Bar]
 
diff --git a/test/test_repository.py b/test/test_repository.py
index c80e3a4..81d51bc 100644
--- a/test/test_repository.py
+++ b/test/test_repository.py
@@ -1,17 +1,17 @@
-from typing import List
+from typing import List, Optional, cast
 
 import mongomock
 import pytest
 from bson import ObjectId
 from pydantic import BaseModel, Field
 
-from pydantic_mongo import AbstractRepository, ObjectIdField
+from pydantic_mongo import AbstractRepository, PydanticObjectId
 from pydantic_mongo.errors import PaginationError
 
 
 class Foo(BaseModel):
     count: int
-    size: float = None
+    size: Optional[float] = None
 
 
 class Bar(BaseModel):
@@ -20,9 +20,9 @@ class Bar(BaseModel):
 
 
 class Spam(BaseModel):
-    id: ObjectIdField = None
-    foo: Foo = None
-    bars: List[Bar] = None
+    id: Optional[PydanticObjectId] = None
+    foo: Optional[Foo] = None
+    bars: Optional[List[Bar]] = None
 
 
 class SpamRepository(AbstractRepository[Spam]):
@@ -49,7 +49,7 @@ def test_save(self, database):
             "bars": [{"apple": "x", "banana": "y"}],
         } == database["spams"].find()[0]
 
-        spam.foo.count = 2
+        cast(Foo, spam.foo).count = 2
         spam_repository.save(spam)
 
         assert {
@@ -147,6 +147,8 @@ def test_find_by_id(self, database):
         spam_repository = SpamRepository(database=database)
         result = spam_repository.find_one_by_id(spam_id)
 
+        assert result is not None
+        assert result.bars is not None
         assert issubclass(Spam, type(result))
         assert spam_id == result.id
         assert "x" == result.bars[0].apple
@@ -171,6 +173,8 @@ def test_find_by(self, database):
         result = spam_repository.find_by({})
         results = [x for x in result]
         assert 2 == len(results)
+        assert results[0].foo is not None
+        assert results[1].foo is not None
         assert 2 == results[0].foo.count
         assert 3 == results[1].foo.count
 
@@ -181,14 +185,6 @@ def test_find_by(self, database):
         results = [x for x in result]
         assert 0 == len(results)
 
-    def test_invalid_model_class(self, database):
-        class BrokenRepository(AbstractRepository[int]):
-            class Meta:
-                collection_name = "spams"
-
-        with pytest.raises(Exception):
-            BrokenRepository(database=database)
-
     def test_invalid_model_id_field(self, database):
         class NoIdModel(BaseModel):
             something: str