Found it:
FormRadio.php Line 111:
// begin the label wrapper
$radio = '<label'
. $this->_htmlAttribs($label_attribs) . '>'
. '<input type="radio"'
. ' name="' . $this->view->escape($name) . '"'
. ' value="' . $this->view->escape($opt_value) . '"';
change to
// begin the label wrapper
$radio = '<label
for="val'.$this->view->escape($opt_value).'"'
. $this->_htmlAttribs($label_attribs) . '>'
. '<input type="radio"'
. ' id=val'.$this->view->escape($opt_value).''
. ' name="' . $this->view->escape($name) . '"'
. ' value="' . $this->view->escape($opt_value) . '"';