U.K.-based Yoyo announced a $10 million Series A round of funding today, bringing the startup’s total to $15 million. The round was led by Imperial Innovations, an affiliate of Imperial College, where Yoyo piloted its mobile payments app. Investors Taavet Hinrikus, Philip Riese, and Michael Tobin also contributed.

The startup will use the funding to bolster engineering and expand its team.

Yoyo also plans to expand internationally and hopes to launch at five U.S.-based colleges by the end of 2015. Yoyo piloted operations at Imperial College in London. The mobile wallet is now available at 15 other British universities, where Yoyo payments total up to 50% of all transactions on campus.

Yoyo’s platform, which is aimed at closed environments such as universities and airlines, sees 150k transactions per month. This earns it a spot as one of Britain’s largest mobile wallets, second only to Starbucks’ payment app.

The mobile payments app boasts convenience, and its built-in reward system keeps customers coming back. Yoyo has a stickiness rate of 80% and, on average, its users spend more than non-users.

We covered Yoyo in our Finovate Debuts series earlier this year. The company unveiled its mobile wallet technology at FinovateEurope 2015 in London.