How to add a datetime object as custom property to a blender object I'm trying to add a datetime as property to an object like so:

from datetime import datetime
obj = bpy.context.active_object
obj['somedate'] = datetime.strptime('1900-01-01', '%Y-%m-%d')


...and get an runtime TypError about datetime.datetime not being supported as id-property.

Is there a simple way to add this support? (...or is it easier to work with string properties and convert as needed with strptime/strftime?)
import bpy

from datetime import datetime
obj = bpy.context.active_object
obj['somedate'] = str(datetime.strptime('1900-01-01', '%Y-%m-%d'))