lib/PublicInbox/WWW.pm | 2 +-

diff --git a/lib/PublicInbox/WWW.pm b/lib/PublicInbox/WWW.pm
index b0fad7fed256e62af666cb91ef096ba02716ae80..f41f98eda0ff704c2fa55d1e3c4fb693ddec1d20 100644
--- a/lib/PublicInbox/WWW.pm
+++ b/lib/PublicInbox/WWW.pm
@@ -102,7 +102,7 @@ 	} elsif ($path_info =~ m!$INBOX_RE/(?:([0-9]+)/)?
 				($PublicInbox::GitHTTPBackend::ANY)\z!ox) {
 		my ($part, $path) = ($2, $3);
 		invalid_inbox($ctx, $1) || serve_git($ctx, $part, $path);
-	} elsif ($path_info =~ m!$INBOX_RE/([\w-]+).mbox\.gz\z!o) {
+	} elsif ($path_info =~ m!$INBOX_RE/([a-zA-Z0-9_\-]+).mbox\.gz\z!o) {
 		serve_mbox_range($ctx, $1, $2);
 	} elsif ($path_info =~ m!$INBOX_RE/$MID_RE/$END_RE\z!o) {
 		msg_page($ctx, $1, $2, $3);