"srcache_default_expire" directive invalid value" in when using "ms" (milliseconds)

[jfloodnet]

The README.md states
Time units supported are "s"(seconds), "ms"(milliseconds), "y"(years), "M"(months), "w"(weeks), "d"(days), "h"(hours), and "m"(minutes). For example

            srcache_default_expire 500ms;