Update the check for regex to be a bit more strict in what it checks for.

Updated to this: http://regexplained.co.uk/#eyJwYXR0ZXJuIjoiKFtcXFtcXC9dW14sXSpbXFxdXFwvXXxcXFxcW2JkbnJzdHddfFxce1swLTldKyw/KFswLTldKyk/XFx9KSJ9