Google is shutting down Google Checkout in favor of Google Wallet. They’re billing the change as “building one wallet.”

It makes sense when you think of it that way. Why have different payment platforms? Go with the one that you’re betting on for the future. Just make the transition easy.

Google says it is taking all of the functionality of Google Checkout and merging it with Google Wallet, so it shouldn’t be too drastic a change for users, at least in theory.

“We’re committed to upgrading our payment solutions for merchants while ensuring they’re able to process payments without interruption during the holidays — so shoppers using Google Wallet will be able to make purchases seamlessly on merchant sites that accept Google Checkout,” says Google Wallet Product Manager Ben Lee. “Early next year, we will work closely with our merchant partners to switch to the Google Wallet logo and share details on new and upcoming features.”

Discussing the consumer side of things, Lee says, “When you shop with merchants that accept Google Wallet or Google Checkout, just use your Google Wallet username and password to complete your purchase — there’s no need to pull out your credit card or enter your shipping address with every transaction.”

Starting today, you should be able to add a Citi MasterCard to the Google Wallet mobile app, which will also be available for use when you show with Google Wallet online.

Current Google Checkout users can automatically transition their accounts to Gogole Wallet the next time they sign in or make a purchase online. Purchase history info is available here.