Set fuses to:

CKDIV8=0 (enabled)
CKOUT=1 (disabled)
CKSEL=1101 (3-8MHz crystal)
SUT=01 (BOD enabled)
BODLEVEL=100 (4.3V)
WDTON=0 (Watchdog Timer always on)

-- or --

hfuse=11001001 (0xc9)
lfuse=01011101 (0x5d)
