Ariana Grande's rapper ex-boyfriend has died aged just 26, according to TMZ.
The rapper - who split with singer Ariana back in May - was reportedly found around lunchtime at his San Fernando Valley home.
The pair had dated for nearly two years and following their split said they would remain "the closest of friends".
Miller is reported to have had recent problems with substance abuse after he crashed his car in May and was arrested.
TMZ reports he fled the scene but cops say he later confessed at his home.
After his arrest Ariana tweeted: "Pls take care of yourself."
After their breakup, Ariana said: "I am not a babysitter or a mother and no woman should feel that they need to be.
"I have cared for him and tried to support his sobriety & prayed for his balance for years.
"Of course I didn't share about how hard or scary it was while it was happening but it was."
A male friend is understood to have made the emergency call from Mac's home.
Audio from the emergency dispatch reveals they were called for a patient in cardiac arrest.
An investigation into his death has been launched and a coroner's van arrived at the scene at 2:30pm yesterday
Mac and Ariana went public with their romance in August 2016.
Insiders explained the pair decided to split after their work schedules became too busy but they still "love each other dearly".
Ariana first met Mac when they recorded The Way together in 2013, and the pop star admitted last year she had had feelings for him for a long time before they got together romantically.
She said: "We have loved and adored and respected each other since the beginning, since before we even met, just because we were fans of each other's talent."
In a statement released after his death the star's family said: “Malcolm McCormick, known and adored by fans as Mac Miller, has tragically passed away at the age of 26.
“He was a bright light in this world for his family, friends and fans. Thank you for your prayers. Please respect our privacy. There are no further details as to the cause of his death at this time.”