John Mayer doesn't think Fifth Harmony works without Camila Cabello.

The 39-year-old guitarist took to Instagram Live to share his thoughts on her departure from the girl group, comprising of Ally Brooke, Normani Kordei, Dinah Jane and Lauren Jauregui - and even suggested what the 'Work from Home' hitmakers would sound like if he were to join them.

Going through notes on the keyboard, he explained: "So I like Fifth Harmony, but then Camila left the band and now it's just this. Do you see what I'm saying? They need this. All they have is this. So they need to get this. 

"If you really wanted to add me, you get this. And that is one too many notes. Point being... hi Camila."

It's not the first time the 'Gravity' hitmaker has spoken about the 20-year-old beauty's exit.

In January, he wrote: "Fifth Harmony is a talented group of young ladies."

And said that Lauren, 20, will be the next big star. At the time, he wrote: "Lauren feels like the next star."

And the girls even Photoshopped an image of the four of them with Mayer. Alongside the photo, they wrote: "..we know numbers can be tricky sometimes @johnmayer #BeThe5thChallenge 5/5 (sic)"

To which he replied: "Oh will I? 7/27... Drops mic (sic)" 

Meanwhile, Cabello's solo career is going from strength to strength.

The 'Bad Things' singer recently hit the studio with OneRepublic's Ryan Tedder to work on a song for her debut solo record. The 'Counting Stars' hitmaker took to Twitter in the early hours of yesterday morning (March 5) to share a video that gives fans an insight as to what they've been working on together. The clip shows someone walk in on them and ask: "Did you guys get the last line of that chorus yet?" And in response the pair clapped simultaneously.  

Watch the video John Mayer uploaded below: