Back in 2008 the Democratic Republic of Congo struck a big deal with Beijing.
China's state owned firms would build hospitals and roads in return for revenues from copper and cobalt mines.
Thirteen years on, critics say few of the promised benefits have materialised.
Now a new report by a global anti-corruption body, seen by Reuters, calls the deal 'unconscionable'.
It urges Congo to cancel an amendment signed in secret in 2017, which sped up payments to Chinese investors.
The report may be welcomed by President Felix Tshisekedi.
On a recent visit to a mining area, he told residents he was re-evaluating relations with Chinese investors:
"We have noticed for some years that people come into our country with empty hands and pretend to be entrepreneurs and leave with billions in their pockets but we remain poor."
Tshisekedi's move marks a rare push-back by Congo.
Now the full report will be published later this month by the Extractive Industries Transparency Initiative, which tracks money flows in oil and mining.
It has no legal force, but could bolster Congo's bid to rejig the China deal, and maybe make Beijing change its approach elsewhere.
Jean Pierre Okenda is an expert on Congolese mining:
"I think that this report might make the Chinese government think twice in terms of making deals in countries with weak governance, countries where the administration is not efficient."
Global industry will be watching too.
DR Congo is the world's leading producer of cobalt, now of huge strategic importance as a key component in batteries.