[Spridgets] Positive ground phone charger

[Gmari2]

Greetings group,
Like an idiot, i installed a cigerette lighter to the Sprite in hopes of
having a usable phone charger.  The car is positive ground.  The lighter
itself works great at heating the coil to light a smoke.  But what is now
painfully obvios is that it will not work at charging a cell phone.
Other than converting the car to negative ground, can anyone reccomend a
solution?
Thanks,
George