preg_match problem

Hi all, I have a simple checking like if (preg_match("/[\w\x2F]{6,}/",$a)) as I would like to allow all "word characters" as mentioned at http://hu2.php.net/manual/hu/reference.pcre.pattern.syntax.php plus the '/' character, and at least 6 characters. But it throws Warning: preg_match(): Unknown modifier ']' and returns false for "abc/de/ggg" which string should be okay. If I omit the "\x2F", everything works fine but "/" characters are not allowed. Anyone knows what I'm doing wrong? Maybe "/" characters can not be put in patterns like this? Thanks in advance, Zoltán Németh