lib/PublicInbox/TestCommon.pm | 9 +++++++++
 t/extsearch.t                 | 4 ++--
 t/nntpd.t                     | 3 +--
 t/v2writable.t                | 2 +-

diff --git a/lib/PublicInbox/TestCommon.pm b/lib/PublicInbox/TestCommon.pm
index 55d82fc08592d0efa1370e1aeb7f4e2886075d49..333791b4cd5d9d5d858572866fdd343e572f1e66 100644
--- a/lib/PublicInbox/TestCommon.pm
+++ b/lib/PublicInbox/TestCommon.pm
@@ -117,6 +117,12 @@ 	}
 	1;
 }
 
+my %IPv6_VERSION = (
+	'Net::NNTP' => 3.00,
+	'Mail::IMAPClient' => 3.40,
+	'HTTP::Tiny' => 0.042,
+);
+
 sub require_mods {
 	my @mods = @_;
 	my $maybe = pop @mods if $mods[-1] =~ /\A[0-9]+\z/;
@@ -166,6 +172,9 @@ 			# by libnet, at least:
 			# https://rt.cpan.org/Ticket/Display.html?id=100529
 				!eval{ IO::Socket::SSL->VERSION(2.007); 1 }) {
 			push @need, $@;
+		}
+		if (defined(my $v = $IPv6_VERSION{$mod})) {
+			$ENV{TEST_IPV4_ONLY} = 1 if !eval { $mod->VERSION($v) };
 		}
 	}
 	return unless @need;
diff --git a/t/extsearch.t b/t/extsearch.t
index 2d7375d63f9a6467f3b98b80da2715589ad4b573..6cbe52626830d5886054072a594b06c31725c5d0 100644
--- a/t/extsearch.t
+++ b/t/extsearch.t
@@ -13,8 +13,6 @@ require PublicInbox::Search;
 use_ok 'PublicInbox::ExtSearch';
 use_ok 'PublicInbox::ExtSearchIdx';
 use_ok 'PublicInbox::OverIdx';
-my $sock = tcp_server();
-my $host_port = tcp_host_port($sock);
 my ($home, $for_destroy) = tmpdir();
 local $ENV{HOME} = $home;
 mkdir "$home/.public-inbox" or BAIL_OUT $!;
@@ -125,6 +123,8 @@ }
 
 SKIP: {
 	require_mods(qw(Net::NNTP), 1);
+	my $sock = tcp_server();
+	my $host_port = tcp_host_port($sock);
 	my ($out, $err) = ("$home/nntpd.out.log", "$home/nntpd.err.log");
 	my $cmd = [ '-nntpd', '-W0', "--stdout=$out", "--stderr=$err" ];
 	my $td = start_script($cmd, undef, { 3 => $sock });
diff --git a/t/nntpd.t b/t/nntpd.t
index 34e9e1b45462675d175f807fc6a1bdc38477334f..d352c3c14805aa523cd15518f1a4789c97416933 100644
--- a/t/nntpd.t
+++ b/t/nntpd.t
@@ -2,10 +2,9 @@ #!perl -w
 # Copyright (C) all contributors <meta@public-inbox.org>
 # License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
 use strict; use v5.10.1; use PublicInbox::TestCommon;
-require_mods(qw(DBD::SQLite));
+require_mods(qw(DBD::SQLite Net::NNTP));
 use PublicInbox::Eml;
 use Socket qw(IPPROTO_TCP TCP_NODELAY);
-use Net::NNTP;
 use Sys::Hostname;
 use POSIX qw(_exit);
 use Digest::SHA;
diff --git a/t/v2writable.t b/t/v2writable.t
index 477621e24d011449e611f14caf567b32cfb645ab..ad946338e0aeb730ba5fa6b6bb6ca41cd61d12dd 100644
--- a/t/v2writable.t
+++ b/t/v2writable.t
@@ -149,7 +149,7 @@ 	is_deeply([values(%uniq)], [3], '3 queries, 3 results');
 }
 
 {
-	use Net::NNTP;
+	require_mods('Net::NNTP', 1);
 	my $err = "$inboxdir/stderr.log";
 	my $out = "$inboxdir/stdout.log";
 	my $group = 'inbox.comp.test.v2writable';