diff --git a/umongo/fields.py b/umongo/fields.py
index 2cb87e3..c2ba09a 100644
--- a/umongo/fields.py
+++ b/umongo/fields.py
@@ -248,9 +248,7 @@ class StrictDateTimeField(BaseField, ma_bonus_fields.StrictDateTime):
             ret = self._set_tz_awareness(value)
         else:
             ret = super()._deserialize(value, attr, data)
-        # MongoDB stores datetimes with a millisecond precision.
-        # Don't keep more precision in the object than in the database.
-        return ret.replace(microsecond=round(ret.microsecond, -3))
+        return _round_to_millisecond(ret)
 
     def _deserialize_from_mongo(self, value):
         return self._set_tz_awareness(value)

ValueError: microsecond must be in 0..999999
Hello, all

I've got a new error after the v2.0.0 milestone, likely relating to #172. Here's the error text:

```python
  File "/Users/space/Documents/Programming/dt-blog-platform/api-server/db/objs.py", line 268, in commit
    self.updatedon = datetime.datetime.utcnow()
  File "/var/root/.local/share/virtualenvs/api-server-DI-zCP9m/lib/python3.6/site-packages/umongo/document.py", line 295, in __setattr__
    self._data.set(name, value, to_raise=AttributeError)
  File "/var/root/.local/share/virtualenvs/api-server-DI-zCP9m/lib/python3.6/site-packages/umongo/data_proxy.py", line 152, in set
    value = field._deserialize(value, name, None)
  File "/var/root/.local/share/virtualenvs/api-server-DI-zCP9m/lib/python3.6/site-packages/umongo/fields.py", line 245, in _deserialize
    return ret.replace(microsecond=round(ret.microsecond, -3))
ValueError: microsecond must be in 0..999999
```

My guess is something funky is going on either with my system, or maybe the round isn't working properly? Not too sure, but this should be a simple one.

The way I did this is set a `StrictDateTimeField` equal to `datetime.datetime.utcnow()` in an overriden `commit` method. Ex:

```python
@instance.register
class Foo(Document):
    name = fields.StringField()
    updatedon = fields.StrictDateTimeField()

    def commit(self, *args, **kwargs):
        self.updatedon = datetime.datetime.utcnow()
        return super(Foo, self).commit(*args, **kwargs)
```

This error happens when calling the commit method on the object.

Thanks in advance!
diff --git a/tests/test_fields.py b/tests/test_fields.py
index d4d2133..9b90b05 100644
--- a/tests/test_fields.py
+++ b/tests/test_fields.py
@@ -243,6 +243,11 @@ class TestFields(BaseTest):
         s = MySchema()
         data, _ = s.load({'a': dt.datetime(2016, 8, 6, 12, 30, 30, 123456)})
         assert data['a'].microsecond == 123000
+        data, _ = s.load({'a': dt.datetime(2016, 8, 6, 12, 59, 59, 999876)})
+        assert data['a'].hour == 13
+        assert data['a'].minute == 0
+        assert data['a'].second == 0
+        assert data['a'].microsecond == 0
 
     def test_date(self):
 

pip install -e .[dev]
parse_log_pytest
requirements.txt
pytest pytest-cov
apt-get update apt-get install -y gcc
3.7
requirements/base.txt
pytest --no-header -rA --tb=line --color=no -p no:cacheprovider -W ignore::DeprecationWarning
certifi @ file:///croot/certifi_1671487769961/work/certifi
coverage==7.2.7
dnspython==2.3.0
exceptiongroup==1.2.2
importlib-metadata==6.7.0
iniconfig==2.0.0
marshmallow==2.21.0
packaging==24.0
pluggy==1.2.0
pymongo==4.7.3
pytest==7.4.4
pytest-cov==4.1.0
python-dateutil==2.9.0.post0
six==1.17.0
tomli==2.0.1
typing_extensions==4.7.1
-e git+https://github.com/Scille/umongo.git@7f8c4cd62e61d1a62a70706f1780248bb3c3ad2a#egg=umongo
zipp==3.15.0

name: umongo
channels:
  - defaults
  - https://repo.anaconda.com/pkgs/main
  - https://repo.anaconda.com/pkgs/r
  - conda-forge
dependencies:
  - _libgcc_mutex=0.1=main
  - _openmp_mutex=5.1=1_gnu
  - ca-certificates=2025.2.25=h06a4308_0
  - certifi=2022.12.7=py37h06a4308_0
  - ld_impl_linux-64=2.40=h12ee557_0
  - libffi=3.4.4=h6a678d5_1
  - libgcc-ng=11.2.0=h1234567_1
  - libgomp=11.2.0=h1234567_1
  - libstdcxx-ng=11.2.0=h1234567_1
  - ncurses=6.4=h6a678d5_0
  - openssl=1.1.1w=h7f8727e_0
  - pip=22.3.1=py37h06a4308_0
  - python=3.7.16=h7a1cb2a_0
  - readline=8.2=h5eee18b_0
  - setuptools=65.6.3=py37h06a4308_0
  - sqlite=3.45.3=h5eee18b_0
  - tk=8.6.14=h39e8969_0
  - wheel=0.38.4=py37h06a4308_0
  - xz=5.6.4=h5eee18b_1
  - zlib=1.2.13=h5eee18b_1
  - pip:
      - coverage==7.2.7
      - dnspython==2.3.0
      - exceptiongroup==1.2.2
      - importlib-metadata==6.7.0
      - iniconfig==2.0.0
      - marshmallow==2.21.0
      - packaging==24.0
      - pluggy==1.2.0
      - pymongo==4.7.3
      - pytest==7.4.4
      - pytest-cov==4.1.0
      - python-dateutil==2.9.0.post0
      - six==1.17.0
      - tomli==2.0.1
      - typing-extensions==4.7.1
      - zipp==3.15.0
prefix: /opt/conda/envs/umongo

tests/test_fields.py::TestFields::test_strictdatetime
tests/test_fields.py::TestRequired::test_required tests/test_fields.py::TestRequired::test_required_nested tests/test_fields.py::TestFields::test_basefields tests/test_fields.py::TestFields::test_datetime tests/test_fields.py::TestFields::test_date tests/test_fields.py::TestFields::test_dict tests/test_fields.py::TestFields::test_dict_default tests/test_fields.py::TestFields::test_list tests/test_fields.py::TestFields::test_list_default tests/test_fields.py::TestFields::test_complex_list tests/test_fields.py::TestFields::test_objectid tests/test_fields.py::TestFields::test_reference tests/test_fields.py::TestFields::test_reference_lazy tests/test_fields.py::TestFields::test_generic_reference tests/test_fields.py::TestFields::test_decimal
umongo/fields.py
umongo/fields.py