lib/PublicInbox/View.pm |  2 +-
 lib/PublicInbox/WWW.pm  |  2 +-
 t/psgi_attach.t         | 17 ++++++++++++++++-

diff --git a/lib/PublicInbox/View.pm b/lib/PublicInbox/View.pm
index ec5f39076eccc64d15d87699ca8919e2b4d3200f..21949812d5789131bb6bba536ed582e334c38edb 100644
--- a/lib/PublicInbox/View.pm
+++ b/lib/PublicInbox/View.pm
@@ -261,7 +261,7 @@ 	my $desc = $part->header('Content-Description');
 	$desc = $fn unless defined $desc;
 	$desc = '' unless defined $desc;
 	my $sfn;
-	if (defined $fn && $fn =~ /\A[\w\.-]+[a-zA-Z0-9]\z/) {
+	if (defined $fn && $fn =~ /\A[[:alnum:]][\w\.-]+[[:alnum:]]\z/) {
 		$sfn = $fn;
 	} elsif ($ct eq 'text/plain') {
 		$sfn = 'a.txt';
diff --git a/lib/PublicInbox/WWW.pm b/lib/PublicInbox/WWW.pm
index 10c2e7caee36e2a46bea6a9d43a1fa41603937bb..5b4d6c185722bdeb98f408acabb258687b40123b 100644
--- a/lib/PublicInbox/WWW.pm
+++ b/lib/PublicInbox/WWW.pm
@@ -23,7 +23,7 @@ use PublicInbox::GitHTTPBackend;
 our $INBOX_RE = qr!\A/([\w\.\-]+)!;
 our $MID_RE = qr!([^/]+)!;
 our $END_RE = qr!(T/|t/|R/|t\.mbox(?:\.gz)?|t\.atom|raw|)!;
-our $ATTACH_RE = qr!(\d[\.\d]*)-([\w\.-]+[a-zA-Z0-9])!i;
+our $ATTACH_RE = qr!(\d[\.\d]*)-([[:alnum:]][\w\.-]+[[:alnum:]])!i;
 
 sub new {
 	my ($class, $pi_config) = @_;
diff --git a/t/psgi_attach.t b/t/psgi_attach.t
index 43018e85d1ce6bf3fec6d41cfebc356aec822650..ef116c6af13f63fab9368ea91ed13ac2b39da5c0 100644
--- a/t/psgi_attach.t
+++ b/t/psgi_attach.t
@@ -36,6 +36,7 @@ 	is(8, length($buf), 'read some random data');
 	my $qp = "abcdef=g\n==blah\n";
 	my $b64 = 'b64'.$buf."\n";
 	my $txt = "plain\ntext\npass\nthrough\n";
+	my $dot = "dotfile\n";
 	my $parts = [
 		Email::MIME->create(
 			attributes => {
@@ -57,6 +58,12 @@ 				filename => 'noop.txt',
 				content_type => 'text/plain',
 			},
 			body => $txt),
+		Email::MIME->create(
+			attributes => {
+				filename => '.dotfile',
+				content_type => 'text/plain',
+			},
+			body => $dot),
 	];
 	my $mime = Email::MIME->create(
 		parts => $parts,
@@ -76,7 +83,8 @@ 		my $res;
 		$res = $cb->(GET('/test/Z%40B/'));
 		my @href = ($res->content =~ /^href="([^"]+)"/gms);
 		@href = grep(/\A[\d\.]+-/, @href);
-		is_deeply([qw(1-queue-pee 2-bayce-sixty-four 3-noop.txt)],
+		is_deeply([qw(1-queue-pee 2-bayce-sixty-four 3-noop.txt
+				4-a.txt)],
 			\@href, 'attachment links generated');
 
 		$res = $cb->(GET('/test/Z%40B/1-queue-pee'));
@@ -97,6 +105,13 @@ 		ok(length($txt_res) >= length($txt),
 			'plain text almost matches');
 		like($txt_res, qr/\n\z/s, 'trailing newline exists in text');
 		is(index($txt_res, $txt), 0, 'plain text not truncated');
+
+		$res = $cb->(GET('/test/Z%40B/4-a.txt'));
+		my $dot_res = $res->content;
+		ok(length($dot_res) >= length($dot), 'dot almost matches');
+		$res = $cb->(GET('/test/Z%40B/4-any-filename.txt'));
+		is($res->content, $dot_res, 'user-specified filename is OK');
+
 	});
 }
 done_testing();