module-assistant on Debian with a custom Kernel

If you get this error:

# m-a -v -k"/usr/src/linux-headers-$(uname -r)/" a-i openafs
Updated infos about 1 packages
Bad kernel version specification at /usr/bin/m-a line 568, <$apt> line 9.

You should also use the -l (ell) option:

# m-a -vd -k"/usr/src/linux-headers-$(uname -r)/" -l $(uname -r) a-i openafs