lib/PublicInbox/Config.pm | 4 +---

diff --git a/lib/PublicInbox/Config.pm b/lib/PublicInbox/Config.pm
index 577337dc8a024d375be2db4f72cffb0365be2ffb..cd8957a1276bb0fa01becd74bf47c61158aec127 100644
--- a/lib/PublicInbox/Config.pm
+++ b/lib/PublicInbox/Config.pm
@@ -424,9 +424,7 @@ 			$ibx->{$k} = _array($v);
 		}
 	}
 
-	my $name = $pfx;
-	$name =~ s/\Apublicinbox\.//;
-
+	my $name = substr($pfx, length('publicinbox.'));
 	if (!valid_inbox_name($name)) {
 		warn "invalid inbox name: '$name'\n";
 		return;