My fuel tank leaks around the fitting where the fuel sender is.

It just needs a little help sealing up. I thought to use silicone but that only works with oil and coolant, apparently fuel makes it go soft and then disolves it.

What sealant will work that is fuel safe?

I'm aftre something like silicone, not POR15. I just need to seal the fuel sender in a little better than the rubber gasket that comes with it.