lib/PublicInbox/Config.pm | 2 +-

diff --git a/lib/PublicInbox/Config.pm b/lib/PublicInbox/Config.pm
index e0329ebf34b945928888879471c8ace7efe26808..509de0a0b844784f6d8c05bbc5d1ac741dd4902b 100644
--- a/lib/PublicInbox/Config.pm
+++ b/lib/PublicInbox/Config.pm
@@ -93,7 +93,7 @@ 	my ($self, $cb) = @_;
 	# may auto-vivify if config file is non-existent:
 	foreach my $section (@{$self->{-section_order}}) {
 		next if $section !~ m!\Apublicinbox\.([^/]+)\z!;
-		$self->{"publicinbox.$1.mainrepo"} or next;
+		defined($self->{"publicinbox.$1.mainrepo"}) or next;
 		my $ibx = lookup_name($self, $1) or next;
 		$cb->($ibx);
 	}