Britney Spears’ ex-husband Kevin Federline has asked for an increase in child support after seeing the success of her four-year Las Vegas residency.

Recently Federline’s attorney reportedly sent the singer a letter indicating that he would like to renegotiate the $20,000 monthly payment he receives currently for their two sons, Preston, 12, and Jayden, 11.

The former couple had decided on that amount after Spears lost sole physical and legal custody of the children and was placed in a still-ongoing conservatorship under the care of her father during their 2008 divorce. Looking at how her residency grossed over $137 million in four short years, Federline is looking to cash in, by claiming that he beileves the success of her show was “in part because the boys have been in her life.”

Federline feels he’s entitled to an increased child support in order to “recognize the sacrifices he has made because he has gone above and beyond what most people would do in this situation.”

Spears and Federline are both hoping to reach an agreement outside of court.