Auth Proxy Whitelist and CIDR

When configuring the auth proxy whitelist, it doesn’t seem to be accepting CIDR style ip’s.

I’m using the following:

whitelist = 172.18.0.0/24

which as I understand it should accept IP’s in the range: 172.18.0.0 -> 172.18.0.255, but I get the following error:

Request for user (user@redacted.com) from 172.18.0.3 is not from the authentication proxy

if I set it to 172.18.0.3, then it works fine. The docs seem to suggest that CIDR style address should work, unless I’m misunderstanding something?

Using Grafana 5.4.2.

Thanks!