Ever walk away from an impulse buy cursing yourself for using the wrong card? There’s an app for that now–well, a fintech.

Curve, a London-based fintech that currently allows users to aggregate multiple bank cards together using one physical card and a mobile wallet, is rolling out what’s been dubbed as its “Financial Time Travel feature”– a way to retroactively choose which card is used for a past transaction.

Previous to the startup’s new “time travel” feature, announced yesterday, Curve worked like any other card-switching startup  (think Stratos or Coin, or a few others, plus a physical bank card).

A Curve user first loads multiple bank and credit cards into the mobile wallet, picks which one that will be charged, and then uses the accompanying physical card for the charges.

Curve’s own card is powered by Mastercard, though (naturally) credit cards of all kinds are welcome. Curve’s card also works with all of the myriad physical payment terminals one will come across in daily life–chip and pin, contactless, etc.

However, there is still the issue of remembering to switch the cards one wants to use in between transactions–not to mention which card one has loaded in the first place. These pain points may be part of the reason many card-switching startups are struggling, but Curve’s feature appears to solve many of them.

The new feature, which was specifically asked for by Curve users (as well as most people with multiple credit cards), gives users a two-week period to decide which of their cards, aggregated in Curve, they want charged for a particular purchase.

For Curve consumers, this means that “oh no” moment at checkout can be entirely circumvented; for businesses, particular credit providers, this means future opportunities, as Curve might be able to push appropriate credit products (such as pre-approved loans) to the consumer before switching the charge to that product.