Square, the other company that Twitter co-founder Jack Dorsey runs, which offers a device anyone can plug into their smartphones to accept credit cards, has announced that 1 million merchants are now using Square.

According to Dorsey, only 8 million merchants in the U.S. even accept credit cards. That’s some pretty good progress on Square’s part.

Dorsey tweeted out:

Square is only available in the U.S. so far, so that million merchant milestone is pretty significant. On the company’s website, it says:

We are beginning to look into other markets, though at the time we can’t officially support banks, cards or merchants outside of the 50 United States and DC. There is no specific timeline for international availability, but rest assured that you’ll be among the first to know when it does happen. This includes US territories such as Puerto Rico and Guam.

Square can process non-U.S. cards as long as they come with a Visa, MasterCard, American Express or Discover logo. There are, however, some caveats. Merchants who process international cards can’t do so through the manual entry feature. Processing the cards is subject to issuer approval, and cardholders may be charged for currency conversion.

Square does not support payment processing outside of the United States.