protected function addCheckFields()
    {
        $check = 1;
        foreach ($this->checkFields as $label => &$value) {
            if ($value instanceof \Zend_Form_Element) {
                $element = $value;
            } else {
                if ($value) {
                    $element = new \Zend_Form_Element_Text('check_' . $check);
                    $element->setAllowEmpty(false);
                    $element->setLabel($label);

                    $validator = new \Zend_Validate_Identical($value);
                    $validator->setMessage(
                            sprintf($this->_('%s is not correct.'), $label),
                            \Zend_Validate_Identical::NOT_SAME
                            );
                    $element->addValidator($validator);

                    $value = $element;
                    $check++;
                } else {
                    // Nothing to check for
                    unset($this->checkFields[$label]);
                    continue;
                }
            }
            $this->addElement($element);
        }
    }