Running dnsmasq with runit

Question

Here's my run script for dnsmasq:

#!/bin/ash
COMMAND="dnsmasq -k -C /etc/dnsmasq.conf"

DIR="$( cd "$( dirname -- "$0" )" >/dev/null 2>&1 && pwd )"
SERVICE_NAME=$(basename ${DIR})

exec ${COMMAND} 2>&1 | sed -e "s/^/\[${SERVICE_NAME}\]: /g"

dnsmasq starts correctly, but runit doesn't seem to track the process. The sed process exits, the runsv process exits and runsvdir loses track of it:

$ ps auwxf
...
root      3264  0.0  0.0    756     4 ?        S    15:22   0:00      |       |   |   |   \_ /sbin/runsvdir /services-enabled
root      3277  0.0  0.0   1640     4 ?        S    15:22   0:00      |       |   |   \_ /bin/ash ./run
nobody    3291  0.1  0.0   1000     4 ?        S    15:22   0:00      |       |   |       \_ dnsmasq -k -C /etc/dnsmasq.conf
...

So periodically runsvdir tries to start it again:

$ ps auwxf
root      3264  0.0  0.0    756     4 ?        S    15:22   0:00      |       |   |   |   \_ /sbin/runsvdir /services-enabled
root      3538  0.2  0.0    744   516 ?        S    15:22   0:01      |       |   |   |       \_ runsv dnsmasq
root     10393  0.0  0.0   1640     4 ?        S    15:28   0:00      |       |   |   |           \_ /bin/ash ./run
root     10397 41.0  0.0    980     4 ?        R    15:28   0:00      |       |   |   |               \_ dnsmasq -k -C /etc/dnsmasq.conf
root     10398  0.0  0.0   1604     4 ?        S    15:28   0:00      |       |   |   |               \_ sed -e s/^/\[dnsmasq\]: /g
root      3277  0.0  0.0   1640     4 ?        S    15:22   0:00      |       |   |   \_ /bin/ash ./run
nobody    3291  0.1  0.0   1000     4 ?        S    15:22   0:00      |       |   |       \_ dnsmasq -k -C /etc/dnsmasq.conf

This dies quickly because the original dnsmasq process already has port 53 open and so the cycle repeats every few seconds.

What's the right way to run dnsmasq here so that this doesn't happen? -k is theoretically meant to prevent dnsmasq from daemonising but that doesn't seem to be working.