Index: bin/authentication_milter
--- bin/authentication_milter.orig
+++ bin/authentication_milter
@@ -15,7 +15,7 @@ use Mail::Milter::Authentication::Protocol::Milter;
 use Mail::Milter::Authentication::Protocol::SMTP;
 
 # CONFIG
-my $pid_file = '/run/authentication_milter.pid';
+my $pid_file = '${VARBASE}/run/authentication_milter.pid';
 my $daemon = 0;
 my $help   = 0;
 my $prefix;
@@ -195,7 +195,7 @@ version 3.20240701
 =item --pidfile <file>
 
   Write the process PID to the given file.
-  defaults to /run/authentication_milter.pid
+  defaults to ${VARBASE}/run/authentication_milter.pid
 
 =item --prefix <dir>
 
