setting log_arp_movements to 0 at boot time

[Al]

My message log gets flooded by arp movement notices, but I'm able to
turn off these messages using the following command:
sysctl net.link.ether.inet.log_arp_movements=0

I read somewhere that I can add this line in my /boot/loader.conf file
to keep it set at boot time:
net.link.ether.inet.log_arp_movements: 0

But that doesn't seem to work. Any ideas?  I'm running 5.4-RELEASE-p9


-Al