diff --git a/config.php b/config.php
index 71cd705a1..c137e648b 100644
--- a/config.php
+++ b/config.php
@@ -5,8 +5,8 @@
 ********************/
 
 define('G5_VERSION', '그누보드5');
-define('G5_GNUBOARD_VER', '5.4.2');
-define('G5_YOUNGCART_VER', '5.4.2');
+define('G5_GNUBOARD_VER', '5.4.2.1');
+define('G5_YOUNGCART_VER', '5.4.2.1');
 
 // 이 상수가 정의되지 않으면 각각의 개별 페이지는 별도로 실행될 수 없음
 define('_GNUBOARD_', true);
diff --git a/install/install_db.php b/install/install_db.php
index 0e22db14f..a71d8fc45 100644
--- a/install/install_db.php
+++ b/install/install_db.php
@@ -319,8 +319,7 @@ if($g5_install || !$result) {
         // 게시판 테이블 생성
         $file = file("../".G5_ADMIN_DIR."/sql_write.sql");
         $file = get_db_create_replace($file);
-
-        $sql = implode($file, "\n");
+        $sql = implode('\n', $file);
 
         $create_table = $table_prefix.'write_' . $tmp_bo_table[$i];
 
diff --git a/lib/pbkdf2.compat.php b/lib/pbkdf2.compat.php
index 6bfada1a9..b1e18001b 100644
--- a/lib/pbkdf2.compat.php
+++ b/lib/pbkdf2.compat.php
@@ -46,7 +46,7 @@ function create_hash($password, $force_compat = false)
 {
     // Generate the salt.
     
-    if (function_exists('mcrypt_create_iv')) {
+    if (function_exists('mcrypt_create_iv') && version_compare( PHP_VERSION, '7.2' , '<' ) ) {
         $salt = base64_encode(mcrypt_create_iv(PBKDF2_COMPAT_SALT_BYTES, MCRYPT_DEV_URANDOM));
     } elseif (@file_exists('/dev/urandom') && $fp = @fopen('/dev/urandom', 'r')) {
         $salt = base64_encode(fread($fp, PBKDF2_COMPAT_SALT_BYTES));