Yup, thought of that :) - but then when I have problems later on (as I always do), the first things the monks would say is use -w (well, after use strict).

Looking at the documentation for the module, it says of the add method:

$obj->add( $key, $value );
Adds a new key/value pair to the hash. $key can be a Regexp or a string (which is compiled into a Regexp).
If $key is already defined, the value will be changed. If $key matches an existing key (but is not the same), a warning will be shown if warnings are enabled.

and I suspect that the final paragraph is coming into play, but I can't see why.

After having read the docs for Tie::RegexpHash, I still haven't found a solution. I'd say that your best bet would be to contact the author.

Yup, having to do that - was trying to get something working quickly and hoped someone else had come across a solution

What I'm trying to do is a simple parser for some commands and I was thinking of using a hash with the keys being regexp's that would match commands and the value's being references to functions - if anyone knows of another way of doing it I'm always willing to change direction mid-flow :)