Savings and investing app Acorns has announced the option for customers to add bitcoin (BTC) exposure for long-term investing.

Acorns offers accounts that can be funded through automatic investments of spare change or deposits of as little as $5 at any time or on a recurring basis. The app recommends an investment plan for users based on goals, employment and income. Acorns offers five diversified portfolios of exchange-traded funds, or ETFs.

With 4.6 million subscribers, it becomes the latest big name in fintech to inch its way into crypto.

“We’ve always been open-minded and flexible to the idea that as other asset classes mature and become something that we can deliver to customers, we would love to include that in the appropriate way,” Acorns Chief Investment Officer Seth Wunder told CoinDesk in an interview. “Cryptocurrency, specifically bitcoin, in our opinion has gotten to that place where it’s an acceptable piece of people’s portfolios.”

Acorns customers can invest up to 5% of their Acorns Invest portfolio in bitcoin through the ProShares Bitcoin Strategy ETF (BITO), a bitcoin futures fund that went public on the New York Stock Exchange last October.

Asked the reasoning behind the 5% exposure cap, Wunder said the math behind the decision was in line with how Acorns thinks about portfolio construction in general when it comes to balancing risk.

“When we look at the portfolios on a risk-adjusted basis, the [bitcoin exposure] range is really between 1% and 5%, depending on the portfolio that people are in. Most of our customers will fall into the 3% to 4% allocation,” he explained.

Wunder said Acorns would eventually add exposure to other cryptocurrencies in the future.

“As people choose to customize their portfolios with us in the future, we will give them the option in time to add other cryptocurrencies to the degree that they want,” said Wunder. “It will be a two-pronged approach: what they have in their portfolios and then what they choose to customize.”

The new program from Acorns follows a $300 million investment announced earlier this month including crypto merchant bank Galaxy Digital.

Correction (March 22, 13:35 UTC): Acorns has 4.6 million subscribers, according to a company representative, not 8.2 million, as was originally reported in this article.