765 ILCS 330/5a
If by reason of a possibility of reverter created more than 40 years prior to the effective date of this amendatory Act, a reverter has come into existence prior to the time of the effective date of this amendatory Act, no person shall commence an action for the recovery of the land or any part thereof based upon such possibility of reverter, after one year from the effective date of this amendatory Act.
If by reason of a breach of condition subsequent created more than 40 years prior to the effective date of this amendatory Act, a right of re-entry has come into existence prior to the time of the effective date of this amendatory Act, no person shall commence an action for the recovery of the land or any part thereof based upon such right of entry or re-entry after one year from the effective date of this amendatory Act, unless entry or re-entry has been actually made to enforce said right before the expiration of such year.
765 ILCS 330/5a