diff --git a/adm/config_form.php b/adm/config_form.php
index 96e64cbb2..6756b5d0b 100644
--- a/adm/config_form.php
+++ b/adm/config_form.php
@@ -27,23 +27,25 @@ if (!isset($config['cf_mobile_new_skin'])) {
 
 if(!isset($config['cf_gcaptcha_mp3'])) {
     sql_query(" ALTER TABLE `{$g4['config_table']}`
-                    ADD `cf_gcaptcha_mp3` VARCHAR(255) NOT NULL DEFAULT '' AFTER `cf_mobile_member_skin` ", TRUE);
+                    ADD `cf_gcaptcha_mp3` VARCHAR(255) NOT NULL DEFAULT '' AFTER `cf_mobile_member_skin` ", true);
 }
 
 if(!isset($config['cf_kcpcert_site_cd'])) {
     sql_query(" ALTER TABLE `{$g4['config_table']}`
-                    ADD `cf_kcpcert_site_cd` VARCHAR(255) NOT NULL DEFAULT '' AFTER `cf_memo_send_point` ", TRUE);
+                    ADD `cf_kcpcert_site_cd` VARCHAR(255) NOT NULL DEFAULT '' AFTER `cf_memo_send_point` ", true);
 }
 
 if(!isset($config['cf_kcpcert_use'])) {
     sql_query(" ALTER TABLE `{$g4['config_table']}`
-                    ADD `cf_kcpcert_use` ENUM('','test','service') NOT NULL DEFAULT '' AFTER `cf_memo_send_point` ", TRUE);
+                    ADD `cf_kcpcert_use` ENUM('','test','service') NOT NULL DEFAULT '' AFTER `cf_memo_send_point` ", true);
 }
 
+sql_query(" ALTER TABLE `{$g4['config_table']}` CHANGE `cf_kcpcert_use` `cf_kcpcert_use` ENUM('','test','service') NOT NULL DEFAULT '' ", false);
+
 if(!isset($config['cf_mobile_pages'])) {
     sql_query(" ALTER TABLE `{$g4['config_table']}`
-                    ADD `cf_mobile_pages` INT(11) NOT NULL DEFAULT '0' AFTER `cf_write_pages` ", TRUE);
-    sql_query(" UPDATE `{$g4['config_table']}` SET cf_mobile_pages = '5' ", TRUE);
+                    ADD `cf_mobile_pages` INT(11) NOT NULL DEFAULT '0' AFTER `cf_write_pages` ", true);
+    sql_query(" UPDATE `{$g4['config_table']}` SET cf_mobile_pages = '5' ", true);
 }
 
 // uniqid 테이블이 없을 경우 생성
diff --git a/bbs/register_form_update.php b/bbs/register_form_update.php
index 55fc56700..0187e8358 100644
--- a/bbs/register_form_update.php
+++ b/bbs/register_form_update.php
@@ -75,7 +75,7 @@ if ($w == '' || $w == 'u') {
     if ($w=='') {
         if ($msg = exist_mb_id($mb_id))     alert($msg);
 
-        if ($config['cf_use_recommend']) {
+        if ($config['cf_use_recommend'] && $mb_recommend) {
             if (!exist_mb_id($mb_recommend))    
                 alert("추천인이 존재하지 않습니다.");
         }
diff --git a/skin/member/basic/register_form.skin.php b/skin/member/basic/register_form.skin.php
index 0abf94bdf..3a724df2a 100644
--- a/skin/member/basic/register_form.skin.php
+++ b/skin/member/basic/register_form.skin.php
@@ -214,7 +214,7 @@ if (!defined('_GNUBOARD_')) exit; // 개별 페이지 접근 불가
 <?php if ($w == "" && $config['cf_use_recommend']) {  ?>
 <tr>
     <th scope="row"><label for="reg_mb_recommend">추천인아이디</label></th>
-    <td><input type="text" name="mb_recommend" id="reg_mb_recommend" class="frm_input" required></td>
+    <td><input type="text" name="mb_recommend" id="reg_mb_recommend" class="frm_input"></td>
 </tr>
 <?php }  ?>
 
@@ -337,7 +337,7 @@ function fregisterform_submit(f)
         }
     }
 
-    if (typeof(f.mb_recommend) != 'undefined') {
+    if (typeof(f.mb_recommend) != 'undefined' && f.mb_recommend.value) {
         if (f.mb_id.value == f.mb_recommend.value) {
             alert('본인을 추천할 수 없습니다.');
             f.mb_recommend.focus();