Anyone currently using the free tier of X, formerly known as Twitter, may soon be asked to hand over a “small” monthly fee to access the service, X owner Elon Musk said on Monday.

The billionaire entrepreneur made the remarks during a livestreamed chat with Israeli prime minister Benjamin Netanyahu.

Musk described the “vast armies of bots” on the social media site as a “super tough problem,” and said that as a result the platform is “moving to having a small monthly payment for use of the X system.”

“It’s the only way I can think of to combat vast armies of bots,” Musk said. “Because a bot costs a fraction of a penny — call it a tenth of a penny — but even if [a bot creator] has to pay a few dollars … the effective cost of bots is very high.” He added that a new payment method would have to be registered for each bot, providing a further constraint on those setting up the automated accounts.

The more nefarious bots can fill up people’s DM inboxes and replies with annoying spam, spread hateful material, or attempt to influence elections, and can end up ruining the user experience.

Musk declined to share details about how much the subscription might cost, or if any benefits or features would be offered in exchange for the payment.

Currently, X has only one subscription, called Premium. The paid tier emerged from Twitter Blue and offers a range of features that include an edit button, prioritized rankings in conversations and search, longer posts, text formatting, and fewer ads.

Premium currently costs up to $115 per year, but it’s expected that any new fee brought in for non-Premium users would be considerably lower.

As with many ideas announced by Musk, it’s impossible to say when non-Premium X users might be asked to pay a monthly fee, if at all.

Musk also said during the live stream that X now has 550 million “monthly users,” though he didn’t say how many of those might be bots rather than humans. Indeed, if the upcoming fee proves effective in eliminating bots and preventing new ones from being set up, X’s user count looks set to dip, at least in the short term, which may affect how much it can charge advertisers. The user base will be further impacted by those who refuse to pay to use X and simply walk away.