In any case in which an employee's credit for an annuity for himself is insufficient--at the time the annuity is fixed or granted--to provide for him a life annuity of $100 a month, a term annuity of equal actuarial value of $100 a month shall be paid in lieu of such lesser amount of life annuity. The same provision shall apply to a widow's annuity if the life annuity is less than $100 a month.
40 ILCS 5/8-157