Compare times: file modification time

[Martin Tschierschke via Digitalmars-d-learn]

With

import std.file:timeLastModified;
auto time = timeLastModified(source);

I get a SysTime, how to check if it is older than an interval (1 
day)?
D/Phobos idiomatically?

(Currently I am using 
(Clock.currTime().toUnixTime-time.toUnixTime)< 60*60*24)).

Regards mt.