Musician and songwriter Plastic Bertrand did not sing on his hit single Ca Plane Pour Moi, an expert linguist has told a court in Belgium.
He spent three months comparing the 1977 punk hit to a 2006 cover version by producer Lou Deprijck - and decided it was the same voice on both.
Deprijck has been taken to court by record label AMC for claiming that it was his voice on the original.
An earlier case, in 2006, ruled that Bertrand was the "legal performer".
Deprijck told Le Parisien newspaper that he was "relieved". "I hope I will finally get my rights," he added.
During his evidence, the expert said he could determine that it was Deprijck singing on the record because of his accent.
"The way the phrases end on each record show that the song could only have been sung by a Ch'ti - otherwise known as someone from the Picard region of France," he said.
"It could therefore not have been Plastic Bertrand - who was born in Brussels - and was surely Monsieur Deprijck."
Deprijck, he went on to explain, hails from West Hainaut, a region sometimes referred to as Picard Walloonia, because people in that French-speaking part of Belgium speak with a Picard accent.
In 2006, Deprijck released his own recording of Ca Plane Pour Moi - marketed as being the "original voice" on the track - which prompted record label AMC to take legal action.
The producer said the case was about honour not money.
Plastic Bertrand - whose real name is Roger Jouret - still denies Deprijck's claims.
"He's making me out to be a crook, but I am an artist, not a crook," he said, threatening to countersue his former producer for defamation.
The original song went to number eight in the UK Top 40 chart in 1978.