diff --git a/bbs/ajax.mb_email.php b/bbs/ajax.mb_email.php
index 6c50300cc..21a7df62c 100644
--- a/bbs/ajax.mb_email.php
+++ b/bbs/ajax.mb_email.php
@@ -5,8 +5,12 @@ include_once(G5_LIB_PATH.'/register.lib.php');
 $mb_email = trim($_POST['reg_mb_email']);
 $mb_id    = trim($_POST['reg_mb_id']);
 
+set_session('ss_check_mb_email', '');
+
 if ($msg = empty_mb_email($mb_email)) die($msg);
 if ($msg = valid_mb_email($mb_email)) die($msg);
 if ($msg = prohibit_mb_email($mb_email)) die($msg);
 if ($msg = exist_mb_email($mb_email, $mb_id)) die($msg);
+
+set_session('ss_check_mb_email', $mb_email);
 ?>
\ No newline at end of file
diff --git a/bbs/ajax.mb_id.php b/bbs/ajax.mb_id.php
index 6b0badd06..6ab21cb3f 100644
--- a/bbs/ajax.mb_id.php
+++ b/bbs/ajax.mb_id.php
@@ -4,9 +4,13 @@ include_once(G5_LIB_PATH.'/register.lib.php');
 
 $mb_id = trim($_POST['reg_mb_id']);
 
+set_session('ss_check_mb_id', '');
+
 if ($msg = empty_mb_id($mb_id))     die($msg);
 if ($msg = valid_mb_id($mb_id))     die($msg);
 if ($msg = count_mb_id($mb_id))     die($msg);
 if ($msg = exist_mb_id($mb_id))     die($msg);
 if ($msg = reserve_mb_id($mb_id))   die($msg);
+
+set_session('ss_check_mb_id', $mb_id);
 ?>
\ No newline at end of file
diff --git a/bbs/ajax.mb_nick.php b/bbs/ajax.mb_nick.php
index 07fc5dcc9..74a289444 100644
--- a/bbs/ajax.mb_nick.php
+++ b/bbs/ajax.mb_nick.php
@@ -5,9 +5,13 @@ include_once(G5_LIB_PATH.'/register.lib.php');
 $mb_nick = trim($_POST['reg_mb_nick']);
 $mb_id   = trim($_POST['reg_mb_id']);
 
+set_session('ss_check_mb_nick', '');
+
 if ($msg = empty_mb_nick($mb_nick)) die($msg);
 if ($msg = valid_mb_nick($mb_nick)) die($msg);
 if ($msg = count_mb_nick($mb_nick)) die($msg);
 if ($msg = exist_mb_nick($mb_nick, $mb_id)) die($msg);
 if ($msg = reserve_mb_nick($mb_nick)) die($msg);
+
+set_session('ss_check_mb_nick', $mb_nick);
 ?>
\ No newline at end of file
diff --git a/bbs/register_form_update.php b/bbs/register_form_update.php
index b61c373d5..ef1392ca6 100644
--- a/bbs/register_form_update.php
+++ b/bbs/register_form_update.php
@@ -79,6 +79,17 @@ if ($w == '' || $w == 'u') {
     if ($msg = valid_mb_id($mb_id))         alert($msg, "", true, true);
     if ($msg = count_mb_id($mb_id))         alert($msg, "", true, true);
 
+    // 이름, 닉네임에 utf-8 이외의 문자가 포함됐다면 오류
+    // 서버환경에 따라 정상적으로 체크되지 않을 수 있음.
+    $tmp_mb_name = iconv('UTF-8', 'UTF-8//IGNORE', $mb_name);
+    if($tmp_mb_name != $mb_name) {
+        alert('이름을 올바르게 입력해 주십시오.');
+    }
+    $tmp_mb_nick = iconv('UTF-8', 'UTF-8//IGNORE', $mb_nick);
+    if($tmp_mb_nick != $mb_nick) {
+        alert('닉네임을 올바르게 입력해 주십시오.');
+    }
+
     if ($w == '' && !$mb_password)
         alert('비밀번호가 넘어오지 않았습니다.');
     if($w == '' && $mb_password != $mb_password_re)
@@ -103,6 +114,14 @@ if ($w == '' || $w == 'u') {
     if ($w=='') {
         if ($msg = exist_mb_id($mb_id))     alert($msg);
 
+        if (get_session('ss_check_mb_id') != $mb_id || get_session('ss_check_mb_nick') != $mb_nick || get_session('ss_check_mb_email') != $mb_email) {
+            set_session('ss_check_mb_id', '');
+            set_session('ss_check_mb_nick', '');
+            set_session('ss_check_mb_email', '');
+
+            alert('올바른 방법으로 이용해 주십시오.');
+        }
+
         // 본인확인 체크
         if($config['cf_cert_use'] && $config['cf_cert_req']) {
             if(trim($_POST['cert_no']) != $_SESSION['ss_cert_no'] || !$_SESSION['ss_cert_no'])
diff --git a/config.php b/config.php
index f969d91a2..081cb309f 100644
--- a/config.php
+++ b/config.php
@@ -5,7 +5,7 @@
 ********************/
 
 define('G5_VERSION', '그누보드5');
-define('G5_GNUBOARD_VER', '5.1.6');
+define('G5_GNUBOARD_VER', '5.1.7');
 
 // 이 상수가 정의되지 않으면 각각의 개별 페이지는 별도로 실행될 수 없음
 define('_GNUBOARD_', true);
diff --git a/plugin/kcaptcha/kcaptcha.lib.php b/plugin/kcaptcha/kcaptcha.lib.php
index 6c0ea5470..8449d1dc7 100644
--- a/plugin/kcaptcha/kcaptcha.lib.php
+++ b/plugin/kcaptcha/kcaptcha.lib.php
@@ -247,7 +247,7 @@ function captcha_html($class="captcha")
     $html .= "\n".'<button type="button" id="captcha_mp3"><span></span>숫자음성듣기</button>';
     $html .= "\n".'<button type="button" id="captcha_reload"><span></span>새로고침</button>';
     $html .= '<input type="text" name="captcha_key" id="captcha_key" required class="captcha_box required" size="6" maxlength="6">';
-    $html .= "\n".'<span id="captcha_info">자동등록방지 영숫자를 순서대로 입력하세요.</span>';
+    $html .= "\n".'<span id="captcha_info">자동등록방지 숫자를 순서대로 입력하세요.</span>';
     $html .= "\n".'</fieldset>';
     return $html;
 }