Limiting random value returned to maximum value of signed 64 bits

[TalibKweli]

Hi,
I was just looking at possibly using MurmurHash3 in a project and I'm assuming if I called MurmurHash3_x64_128 then each of the 64 bit values returned will contain a random value between 1 and the maximum value of an unsigned 64 value (i.e. 18446744073709551615). I wanted to check is there a way I could limit either or both 64 bit values to the maximum size of a signed 64 bit value (i.e. 9223372036854775807)?

Thanks