Sonos cofounder John MacFarlane has hit back at Spotify’s cofounder and CEO Daniel Ek who recently whined about Apple’s platforms not being, in his personal view, open enough to third-party apps like Spotify. In a post on Twitter, MacFarlane called the real irony the fact that the Swedish company operates an even-more closed ecosystem than the Cupertino tech giant.

In a tweet Wednesday, first spotted by Fortune, Sonos cofounder John MacFarlane said it was “solid irony” that Ek, who can be seen pictured top of post, was criticizing Apple’s platform.

Here’s exactly what MacFarlane said:

Having worked closely with both Apple and Spotify, I would say it’s more significantly more difficult to work within Spotify’s ‘closed’ ecosystem than Apple’s. Respect and appreciate both companies, but ‘open’ Spotify is not.

To quickly refresh your memory, Spotify CEO told Bloomberg last week that he was very “encouraged” seeing Apple’s readiness to “open up” to the idea of setting third-party apps as defaults on iOS devices. “It’s moving in the right direction, but,” he added, “we still have many, many steps to go before we consider Apple an open and fair platform.”

If you define openness in terms of how deep an app’s support for third-party services goes, then neither Apple nor Spotify are open. Apple heavily curates its platforms and imposes stringent rules on those wishing to sell software and content to Apple customers.

Spotify, too, is a bit picky when it comes to third-party support. The audio devices from Sonos, for those asking, support both Spotify and Apple Music. Apple’s HomePod speaker currently does not work with third-party music services like Spotify although Apple did recently start letting the Siri digital assistant control third-party music services like Pandora and Spotify.

Spotify, as you know, last year filed an antitrust complaint against Apple with the European Union, saying Apple’s 30 percent cut of subscriptions and limiting functionality on the Apple Watch and Siri heavily disadvantages Spotify and other competing services.

The Swedes company said during a recent earnings call that it had 130 million paid subscribers and 163 million free, ad-supported accounts at the end of the March quarter. This compares to Apple Music’s 60 million paid subscribers reported back in June 2019.

Apple has yet to provide updated numbers since that milestone.