Tech giant Apple has updated its developer guidelines to explicitly ban “mining” cryptocurrencies like bitcoin.

The new rules restrict apps that drain battery, generate excessive heat, or put unnecessary strain on device resources — all of which take place in bitcoin mining.

“Apps, including any third party advertisements displayed within them, may not run unrelated background processes, such as cryptocurrency mining,” Apple said on its website.

It’s unlikely someone could successfully “mine” bitcoin on an iPhone or iPad alone because of the amount of energy and computing power it takes. But Apple’s move could pre-emptively stop future, less energy-intensive digital currencies from being mined on these devices or halt the pooling of multiple devices to accomplish it.

Here’s what Apple’s website says:

2.4 Hardware Compatibility

2.4.2 Design your app to use power efficiently. Apps should not rapidly drain battery, generate excessive heat, or put unnecessary strain on device resources. Apps, including any third party advertisements displayed within them, may not run unrelated background processes, such as cryptocurrency mining.

The guidelines include cryptocurrency but that language remained the same as an archived version of the site recorded in late May by the Internet Archive’s Wayback Machine.

Apple’s crypto-related guidelines were originally set in 2014 after the app store unlisted Coinbase and other cryptocurrency apps, citing an “unresolved issue,” according to Apple Insider, which first reported the guideline updates Monday.

The report didn’t say when Apple updated its policy, and the company did not return a CNBC request for comment.

3.1.5 (b) Cryptocurrencies:

(i) Wallets: Apps may facilitate virtual currency storage, provided they are offered by developers enrolled as an organization.

(ii) Mining: Apps may not mine for cryptocurrencies unless the processing is performed off device (e.g. cloud-based mining).

(iii) Exchanges: Apps may facilitate transactions or transmissions of cryptocurrency on an approved exchange, provided they are offered by the exchange itself.

(iv) Initial Coin Offerings: Apps facilitating Initial Coin Offerings (“ICOs”), cryptocurrency futures trading, and other crypto-securities or quasi-securities trading must come from established banks, securities firms, futures commission merchants (“FCM”), or other approved financial institutions and must comply with all applicable law.

(v) Cryptocurrency apps may not offer currency for completing tasks, such as downloading other apps, encouraging other users to download, posting to social networks, etc.

Cryptocurrency “mining” is essentially math often done by high-powered computers. In order to trade bitcoin, transactions need to be verified through complex math equations, then and added to what’s known as a “distributed ledger.” In return for solving equations “miners” receive bitcoin.

On a computer, that process generates 1,400 watts — the same as one hair dryer, according to bitcoin mining company Coinmint.

Many apps on the iOS store claim to let users mine with power from their personal devices, including “Crypto Coin Miner” and “Cryptocurrency Cloud Mining.” The latter says it lets users “make money and earn cryptocurrencies “without major investment or hassle from direct involvement with hardware or software.”

Bitcoin hit its lowest in two months over the weekend after a relatively small South Korean exchange said it was hacked. The digital currency was trading near $6,726 Monday, according to CoinDesk.