Trouble redeeming Marketing rewards - expiration

[HRB]

We had a customer come in tonight to redeem a $2 reward he had through a Square marketing campaign we sent out on April 23rd. The reward states "This reward expires 6/23/17."

Perhaps it's a California coupon redemption thing but when a coupon says it expires on that day, it typically means that is the last day you can actually use it, not that it expired the day before and you're out of luck if you try to use it today. Our Square POS would not allow us to redeem this for him because it said it was expired.

How do we change the wording so that it says the last day to use it is the day prior? Or is there something else we can do to ensure we aren't making customers angry who come in on the "last day" expecting to use the reward?

Thanks in advance.