Premier League clubs agreed on Friday to amend rules to one of the competition’s key regulations relating to financial fairness following a legal challenge by Manchester City.

After a vote by the top division’s 20 clubs, shareholder loans will now be subject to fair market value. Previously such loans could be offered at lower or no interest rates.

The vote was widely regarded as key to the league being able to enforce its Profit and Sustainability Rules intended to clamp down on out-of-control spending.

The league said in a statement that the rules provided a “robust mechanism to safeguard the financial stability, integrity and competitive balance” of the world’s most popular soccer league.

The vote at a shareholders’ meeting was based on Associated Party Transaction (APT) rules, designed to ensure fair market value is applied to commercial deals with organizations closely aligned to club owners.

The rules are intended to prevent deals such as sponsorships from being artificially inflated, which could undermine the league’s financial rules.

Abu Dhabi-backed City had mounted a legal challenge to the rules after the league found two of its commercial deals not to be at fair market value. Both City and the league claimed victory following a tribunal, supporting arguments on either side.

One of the arguments by City was that shareholder loans should be included in APT rules and that was upheld by the tribunal.

Yet, the four-time defending champion was one of four clubs, including Saudi Arabia-backed Newcastle United, Nottingham Forest and Aston Villa, that voted against amendments on Friday, a person with knowledge of the proceedings told The Associated Press.

The person spoke on the condition of anonymity because individual votes had not been made public.

In a separate case, City faces more than 100 charges of alleged financial breaches from the league.