lib/PublicInbox/LeiOverview.pm | 6 ++----
 lib/PublicInbox/LeiToMail.pm   | 4 ++--
 t/lei.t                        | 2 +-

diff --git a/lib/PublicInbox/LeiOverview.pm b/lib/PublicInbox/LeiOverview.pm
index dcc3088ba8f35e4b45fdf8eefffbb8b6c6f5bb51..cab2b055a5969347d0b55b64db155c7174342baa 100644
--- a/lib/PublicInbox/LeiOverview.pm
+++ b/lib/PublicInbox/LeiOverview.pm
@@ -42,12 +42,10 @@ sub detect_fmt ($$) {
 	my ($lei, $dst) = @_;
 	if ($dst =~ m!\A([:/]+://)!) {
 		$lei->fail("$1 support not implemented, yet\n");
-	} elsif (!-e $dst) {
-		'maildir'; # the default
+	} elsif (!-e $dst || -d _) {
+		'maildir'; # the default TODO: MH?
 	} elsif (-f _ || -p _) {
 		$lei->fail("unable to determine mbox family of $dst\n");
-	} elsif (-d _) { # TODO: MH?
-		'maildir';
 	} else {
 		$lei->fail("unable to determine format of $dst\n");
 	}
diff --git a/lib/PublicInbox/LeiToMail.pm b/lib/PublicInbox/LeiToMail.pm
index 49b5c8ab4cbdb3cb04480725dee6e7473c38cbfd..9d9b57486ecda64c963a071a29b5e6648a734923 100644
--- a/lib/PublicInbox/LeiToMail.pm
+++ b/lib/PublicInbox/LeiToMail.pm
@@ -343,8 +343,8 @@ 		-e $dst && !-d _ and die
 				"$dst exists and is not a directory\n";
 		$lei->{ovv}->{dst} = $dst .= '/' if substr($dst, -1) ne '/';
 	} elsif (substr($fmt, 0, 4) eq 'mbox') {
-		-e $dst && !-f _ && !-p _ and die
-				"$dst exists and is not a regular file\n";
+		(-d $dst || (-e _ && !-w _)) and die
+			"$dst exists and is not a writable file\n";
 		$self->can("eml2$fmt") or die "bad mbox --format=$fmt\n";
 		$self->{base_type} = 'mbox';
 	} else {
diff --git a/t/lei.t b/t/lei.t
index 64cb5f0ef55378d4e4f9f5fb4ef689d304a3cf0e..d49dc01aac1a4bdf2bda4ed5d4945f5a71e7fa2c 100644
--- a/t/lei.t
+++ b/t/lei.t
@@ -187,7 +187,7 @@ 		'error shown');
 	is($? >> 8, 1, 'errored out with exit 1');
 
 	ok(!$lei->(qw(q s:prefix -f mboxcl2 -o), $home), 'bad mbox');
-	like($err, qr!\Q$home\E exists and is not a regular file!,
+	like($err, qr!\Q$home\E exists and is not a writable file!,
 		'error shown');
 	is($? >> 8, 1, 'errored out with exit 1');