Irish heartthrob Niall told fans he was penning tracks with the British band, while popping down to visit Tom Fletcher's newborn baby boy Buzz Michelangelo.
'Story of My Life' singer Niall tweeted that he had "wrote another cool song" with McFly's Dougie Poynter, Danny Jones and Tom.
He later added: "Also I met little Buzz Fletcher last night! Soo cute! @MrsGiFletcher @tommcfly." Tom similarly tweeted: "Last night I wrote a song with @NiallOfficial and then went home and got peed on by my son. Loved both!"
Niall's songwriting skills seemed to have gained him one fan on the night too - Danny's fiancée Georgia Horsley!
Former Miss England Georgia posted a photo of Danny and Niall on the piano, telling fans on Twitter that their songs were helping her to have a good night's sleep.
She said: "A little serenade before bedtime!! I'll sleep like a baby now for sure!! @Dannymcfly @NiallOfficial."
It's not the first time that Niall has teamed up with McFly to write songs, as they also collaborated on several tracks early last year for 1D's album.
Niall is making the most of his free time before he heads off with his One Direction bandmates - Harry Styles, Louis Tomlinson, Liam Payne and Zayn Malik - to kick off their mammoth worldwide stadium tour in May.
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