1 files changed, 1 insertions, 1 deletions
diff --git a/lib/PublicInbox/AltId.pm b/lib/PublicInbox/AltId.pm
index 8ce70e46..3be6c73c 100644
--- a/lib/PublicInbox/AltId.pm
+++ b/lib/PublicInbox/AltId.pm
@@ -22,7 +22,7 @@ sub new {
          my ($class, $ibx, $spec, $writable) = @_;
          my ($type, $prefix, $query) = split(/:/, $spec, 3);
          $type eq 'serial' or die "non-serial not supported, yet\n";
-
+        $prefix =~ /\A\w+\z/ or warn "non-word prefix not searchable\n";
          my %params = map {
                  my ($k, $v) = split(/=/, uri_unescape($_), 2);
                  $v = '' unless defined $v;