lib/PublicInbox/Inbox.pm | 2 +-

diff --git a/lib/PublicInbox/Inbox.pm b/lib/PublicInbox/Inbox.pm
index b3178b987a7a031dc96d134fa7be13423fda1866..04d2f83209851989f402b7161da3b7bb494b2e53 100644
--- a/lib/PublicInbox/Inbox.pm
+++ b/lib/PublicInbox/Inbox.pm
@@ -74,7 +74,7 @@ 	my ($opts, $field, $default) = @_;
 	my $val = $opts->{$field};
 	if (defined $val) {
 		$val = $val->[-1] if ref($val) eq 'ARRAY';
-		$val = undef if $val !~ /\A\d+\z/;
+		$val = undef if $val !~ /\A[0-9]+\z/;
 	}
 	$opts->{$field} = $val || $default;
 }