$OpenBSD: patch-lib_HTTP_Headers_pm,v 1.1.1.1 2014/10/23 19:27:39 nigel Exp $
--- lib/HTTP/Headers.pm.orig	Sat Oct 20 10:11:21 2012
+++ lib/HTTP/Headers.pm	Tue May 27 09:56:24 2014
@@ -150,7 +150,7 @@ sub _header
     my($self, $field, $val, $op) = @_;
 
     Carp::croak("Illegal field name '$field'")
-        if rindex($field, ':') > 1 || !length($field);
+        if ( $field !~ /^X-\w/ && rindex($field, ':') > 1) || !length($field);
 
     unless ($field =~ /^:/) {
 	$field =~ tr/_/-/ if $TRANSLATE_UNDERSCORE;
