T-Pain’s record label Nappy Boy Entertainment is reportedly suing Universal Music Group’s Cash Money Records for unpaid royalties, specifically from Lil Wayne’s albums Tha Carter III (2008) and Tha Carter IV (2011).

According to TMZ, T-Pain claims that he and Nappy Boy signee Young Fyre are owed more than $500,000 for their work across the two records. In particular, T-Pain produced and was featured on Wayne’s “Got Money,” which was the latter’s second highest debut and third consecutive top-ten hit from Tha Carter III on the Billboard Hot 100. Young Fyre has co-production credits on “How to Hate” from Tha Carter IV, which also features T-Pain on vocals.

Both Tha Carter III and Tha Carter IV debuted at No. 1 on the Billboard 200 chart and have since been certified triple-platinum by the RIAA, selling over 3.5 million copies each by 2009 and 2012, respectively.

Wayne has been recording and preparing his final solo album Tha Carter V for the past seven years, but is stuck in his own legal battle with Cash Money: in 2015, the rapper filed a $51 million lawsuit against the label for unpaid royalties, including an unpaid $2 million in advances to record Tha Carter V.

In September 2016, Cash Money co-founder Birdman reportedly presented 20,000 pages of documents arguing that he spent $70 million out of a $100 million advance from parent company UMG on royalty payments, marketing endeavors and recording costs — none of which made it to Wayne and his team. More recently in July 2017, Wayne brought forth new allegations that Birdman and UMG backdated a deal to rob Wayne’s Young Money label (a Cash Money imprint) of future profits.

Wayne is far from alone in his Cash Money beef: the label has had a tumultuous history since its founding in 1991, with dozens of its artists filing lawsuits or quitting the roster entirely.

T-Pain’s lawsuit against Wayne comes six months after the duo released the collaborative project T-Wayne for free on SoundCloud and mixtape sites. While the project was recorded back in 2009, its distribution was delayed due to Wayne’s legal troubles, and was finally released unexpectedly in May 2017 via Nappy Boy and Young Money.

This article originally appeared on Billboard.