lib/PublicInbox/IMAP.pm | 2 +-
 t/imapd.t               | 4 ++++

diff --git a/lib/PublicInbox/IMAP.pm b/lib/PublicInbox/IMAP.pm
index 2d0d005e6f8b71239a342669a03645c0600f82ef..47c08aea0300583d10071f43f3715a8f7b4de2bd 100644
--- a/lib/PublicInbox/IMAP.pm
+++ b/lib/PublicInbox/IMAP.pm
@@ -300,7 +300,7 @@
 # converts a set of message sequence numbers in requests to UIDs:
 sub msn_to_uid_range ($$) {
 	my $msn2uid = $_[0];
-	$_[1] =~ s!([0-9]+)!$msn2uid->[$1 - 1] // ($msn2uid->[-1] + 1)!sge;
+	$_[1] =~ s!([0-9]+)!$msn2uid->[$1 - 1] // ($msn2uid->[-1] // 0 + 1)!sge;
 }
 
 # called by PublicInbox::InboxIdle
diff --git a/t/imapd.t b/t/imapd.t
index cb95fa5d053380760f88c29c80da4ce2b0b240a5..c1c52839f2c1cacec57b949541c4a7c67024d739 100644
--- a/t/imapd.t
+++ b/t/imapd.t
@@ -371,6 +371,10 @@ 	ok($mic->examine($ng), 'EXAMINE on dummy');
 	@hits = $mic->search('SENTSINCE' => '18-Apr-2020');
 	is_deeply(\@hits, [], 'search on dummy with condition works');
 	ok(!$mic->search('SENTSINCE' => '18-Abr-2020'), 'bad month fails');
+	$mic->Uid(0);
+	my $ret = $mic->fetch_hash(2, 'RFC822');
+	is_deeply($ret, {},
+		'MSN FETCH on empty dummy will not trigger warnings, later');
 }); # each_inbox
 
 # message sequence numbers :<