Founding member and guitarist of legendary hard rock group AC/DC Malcolm Young has officially left the band due to illness. Young suffered a severe stroke in April and rumors flew surrounding his retirement, which dismayingly have come true.

The band began recording sessions for their upcoming album, the band’s first in six years, since 2008’s Black Ice. They announced earlier this year plans to go on a 40th anniversary tour. Consequence of Sound shared the news, quoting the press release which says, “due to the nature of [his] condition, he will not be returning to the band.”

While the loss of Young in the Australian band will surely be devastating for fans and a huge adjustment for the AC/DC, the rockers have recruited Young’s nephew Stephen for their new LP Rock or Bust due out December 2 and the upcoming tour. Rock or Bust‘s lead single “Play Ball” will soundtrack Major League Baseball postseason games starting next month.