[SSSD-users] UID < 1000 Configurable?

I was just playing with the sssd local provider and attempting to create a user like 'sss_useradd -u 999 <username>' and I get the error 'The selected UID is outside the allowed range'. Setting UID_MIN in sssd.conf and/or login.defs does not seem to help. Is this a hard-coded limitation?