Until today's release, only MasterCard would work with the NFC payment system, leaving Visa and Discover cardholders with no way to use it. The phone-based "touch-to-pay" application should now work with all three.

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The first new safety feature allows users to remotely disable Google Wallet functionality on their phones if lost or stolen, helping to minimize the losses and ensure that accounts remain safe.

The second and more comprehensive security upgrade changes the way Google Wallet handles payment card information. Instead of being stored on a user's smartphone, all card numbers are now encrypted and kept on Google's own secure servers.

"When you pay in-store, Google actually pays the merchant, and then processes the transaction with your selected credit or debit card. So neither the merchant nor the operating system ever gets your real payment card information," the company says on its new , though it notes that prepaid cards and some Citi MasterCards are still stored locally.