diff --git a/tools/tools/nanobsd/i386.diskimage b/tools/tools/nanobsd/i386.diskimage
index b21f47cee68..6ede3d8dd1f 100644
--- a/tools/tools/nanobsd/i386.diskimage
+++ b/tools/tools/nanobsd/i386.diskimage
@@ -58,11 +58,17 @@ MD=`mdconfig -a -t vnode -f ${TMPFILE0} -x ${SC} -y ${HD}`
 rm -f ${TMPFILE0}
 echo ${SECTS} ${SC} ${HD} ${DATASIZE} | awk '
 	{
+	# size of cylinder in sectors
 	cs = $2 * $3
+	# number of full cylinders
 	cyl = $1 / cs
 	print "g c" cyl " h" $3 " s" $2
+	# Size of data/conf patition, round up to full cylinder
 	dsl = int (($4 + cs - 1) / cs)
+	# Size of code partition cylinder = half the remainder
 	csl = int ((cyl - dsl) / 2)
+	# ... But that could round down, so make the data/conf
+	# use whatever the code partitions do not use.
 	dsl = cyl - csl * 2
 	print "p 1 165 " $2, csl * cs - $2
 	print "p 2 165 " $2 + csl * cs, csl * cs - $2