diff --git a/flaschengeist/controller/userController.py b/flaschengeist/controller/userController.py
index a94c022..a59bbce 100644
--- a/flaschengeist/controller/userController.py
+++ b/flaschengeist/controller/userController.py
@@ -8,7 +8,7 @@ from flask import make_response
 from flask.json import provider
 from sqlalchemy import exc
 from sqlalchemy_utils import merge_references
-from datetime import datetime, timedelta, timezone
+from datetime import datetime, timedelta, timezone, date
 from flask.helpers import send_file
 from werkzeug.exceptions import NotFound, BadRequest, Forbidden
 
@@ -19,7 +19,12 @@ from ..models import Notification, User, Role
 from ..models.user import _PasswordReset
 from ..utils.hook import Hook
 from ..utils.datetime import from_iso_format
-from ..controller import imageController, messageController, pluginController, sessionController
+from ..controller import (
+    imageController,
+    messageController,
+    pluginController,
+    sessionController,
+)
 from ..plugins import AuthPlugin
 
 
@@ -198,7 +203,11 @@ def delete_user(user: User):
         deleted_user = get_user("__deleted_user__", True)
     except NotFound:
         deleted_user = User(
-            userid="__deleted_user__", firstname="USER", lastname="DELETED", display_name="DELETED USER", deleted=True
+            userid="__deleted_user__",
+            firstname="USER",
+            lastname="DELETED",
+            display_name="DELETED USER",
+            deleted=True,
         )
         db.session.add(user)
         db.session.flush()
@@ -209,7 +218,10 @@ def delete_user(user: User):
         db.session.delete(user)
         db.session.commit()
     except exc.IntegrityError:
-        logger.error("Delete of user failed, there might be ForeignKey contraits from disabled plugins", exec_info=True)
+        logger.error(
+            "Delete of user failed, there might be ForeignKey contraits from disabled plugins",
+            exec_info=True,
+        )
         # Remove at least all personal data
         user.userid = f"__deleted_user__{user.id_}"
         user.display_name = "DELETED USER"
@@ -231,7 +243,10 @@ def register(data, passwd=None):
     values = {key: value for key, value in data.items() if key in allowed_keys}
     roles = values.pop("roles", [])
     if "birthday" in data:
-        values["birthday"] = from_iso_format(data["birthday"]).date()
+        if isinstance(data["birthday"], date):
+            values["birthday"] = data["birthday"]
+        else:
+            values["birthday"] = from_iso_format(data["birthday"]).date()
     if "mail" in data and not re.match(r"[^@]+@[^@]+\.[^@]+", data["mail"]):
         raise BadRequest("Invalid mail given")
     user = User(**values)
diff --git a/flaschengeist/models/user.py b/flaschengeist/models/user.py
index 74f7950..21e9604 100644
--- a/flaschengeist/models/user.py
+++ b/flaschengeist/models/user.py
@@ -1,4 +1,6 @@
-from __future__ import annotations  # TODO: Remove if python requirement is >= 3.12 (? PEP 563 is defered)
+from __future__ import (
+    annotations,
+)  # TODO: Remove if python requirement is >= 3.12 (? PEP 563 is defered)
 
 from typing import Optional, Union, List
 from datetime import date, datetime
@@ -45,7 +47,7 @@ class User(db.Model, ModelSerializeMixin):
 
     Attributes:
         id: Id in Database as Primary Key.
-        uid: User ID used by authentication provider
+        userid: User ID used by authentication provider
         display_name: Name to show
         firstname: Firstname of the User
         lastname: Lastname of the User