Senate Republicans made only one big change in a new version of their Senate health bill released Monday: They added a penalty for Americans who let their insurance lapse for 63 days or more.

Under the new provision, those who go without insurance will be locked out of getting coverage for at least six months after they sign up.

The idea is to placate insurers who were alarmed when the bill was released on Thursday without any means to nudge people into the market. This “lockout period” would, in theory, create an incentive for people to have insurance all the time, instead of waiting to sign up when they become ill. But it’s not clear how effective this will really be.