I use SSHFS which uses FUSE. On FreeBSD, I generally compile core components with ports. On attempting to compile fusefs-sshfs, I got an error with fusefs-kmod:

fusefs-kmod  requires the userland sources to be installed. Set SRC_BASE if it is not in /usr/src

Actually the error is fusefs-kmod-xxxxxx for the version. It’s a pretty well known error. I figured it needed the kernel sources. I was wrong (it actually says kernel source if you’re missing that). What it wants, is some of the source for the FreeBSD software. The next question was which software does it want the source for? The answer is “mount” which is in “sbin”. So if you’re getting this error, do a sysinstall and install the source packages for base, sys and sbin and you’ll be right. No need to install ALL userland source like the message implies!