Elon Musk said Tuesday his social media platform X is working to fix its AI chatbot, Grok, after it sided with rival tech chief and OpenAI CEO Sam Altman in an ongoing dispute with Musk, who threatened to sue Apple on Monday night over allegations it favors OpenAI in its app store.

In happier times, OpenAI CEO Sam Altman and Tesla CEO Elon Musk were buddies and business partners, but their bromance notoriously turned sour a long time ago. For the past several years, the two have very publicly hated each other and taken every opportunity they can to dunk on one another’s business pursuits.

Sam Altman is in the process of co-founding a new brain-to-computer interface startup called Merge Labs, and raising funds for it with the capital expected to largely come from OpenAI’s ventures team, unnamed sources told the Financial Times.