Though you most likely use her to test out your most inventive swear words or whip her out when there’s no actual humans around to troll, Siri, Apple iOS’ digital assistant, can actually be pretty useful when you’re not acting like an immature schoolboy.

Its actual purpose is basically to answer any questions you might have. Whether you need restaurant recommendations or you want to know something about World War II, Siri has always been pretty forthcoming, even if it needs to direct you to an outside source.

But it appears then when it comes to certain music questions, Siri gets a little tight-lipped. As NBC News reports, Siri will hold back when asked particular music questions unless the person asking happens to be an Apple Music subscriber.

This intriguing behavior was first spotted by Pandora co-creator Tom Conrad, who took to Twitter to share an image of him asking Siri what the most popular song in the US currently is, only to be told Siri can’t look up music charts unless he’s subscribed to Apple Music.

NBC News and The Verge reportedly confirmed the response appears when asking about music charts. However, when we attempted to recreate the test in the Tone Deaf offices, Siri directed us to a Google search, indicating the issue maybe US-only.

Music charts are indeed part of Apple’s actually-pretty-decent streaming service, so it’s not so strange that Siri wouldn’t have instant access to that info unless the iPhone user is subscribed to Apple Music.

However, as NBC News notes, Siri would ordinarily look up that info by other means. Also worth noting is the fact that Siri will display music charts if you ask the question a bit differently, suggesting it may only be a bug and not a deliberate omission.

For example, when asked ‘What was the number song in 2014’ by NBC, Siri displayed a list of online resources. Both NBC and The Verge have reached out to Apple for comment, but are yet to receive a response.