Malcolm Young, founding member of Australian rock icons AC/DC, has passed away at the age of 64. The band confirmed the news in a statement posted earlier today. Young, who co-founded the group with his brother Angus, had been battling dementia in the past few years.

“As a guitarist, songwriter and visionary he was a perfectionist and a unique man,” the band’s statement reads. “With enormous dedication and commitment he was the driving force behind the band. He always stuck to his guns and did and said exactly what he wanted. He took great pride in all that he endeavored. His loyalty to the fans was unsurpassed.”

After founding AC/DC in 1973, the Young brothers served as the group’s main songwriters, with Malcolm adding rhythm guitar under Angus’ legendary lead, collaborating on classic albums like Back in Black and a number of global rocks hits like “Back in Black,” “Highway to Hell,” “Dirty Deeds Done Dirt Cheap,” “Thunderstruck,” “TNT” and “You Shook Me All Night Long,” among others.

Malcolm announced in 2014 that he would be leaving the band due to his dementia. He did not play on that year’s Rock or Bust but continued to be credited with his brother as co-songwriter. Malcolm was inducted into the Rock and Roll Hall of Fame with AC/DC in 2003.

“As his brother it is hard to express in words what he has meant to me during my life, the bond we had was unique and very special,” Angus writes in the band’s statement on Malcolm’s passing. “He leaves behind an enormous legacy that will live on forever. Malcolm, job well done.”