diff --git a/functions.php b/functions.php
index dc38880..0eedfc3 100644
--- a/functions.php
+++ b/functions.php
@@ -7,7 +7,7 @@
  * @package Sakura
  */
  
-define( 'SAKURA_VERSION', '3.1.4' );
+define( 'SAKURA_VERSION', '3.1.5' );
 define( 'BUILD_VERSION', '1' );
 define( 'JSDELIVR_VERSION', '3.6.7' );
 
@@ -1308,7 +1308,7 @@ function GBsubstr($string, $start, $length) {
 }
  
 function excerpt_length($exp) {
-    if (!function_exists(mb_substr)) {
+    if (!function_exists('mb_substr')) {
         $exp = GBsubstr($exp, 0, 80);
     } else {
         /*
diff --git a/style.css b/style.css
index 9b77c9f..e4d3021 100644
--- a/style.css
+++ b/style.css
@@ -5,7 +5,7 @@ Theme URI: https://2heng.xin/theme-sakura/
 Author: Mashiro, Louie, Fuzzz
 Author URI: http://2heng.xin
 Description: Akina主题分支（原版地址 http://www.akina.pw/themeakina）
-Version: 3.1.3
+Version: 3.1.5
 License: GNU General Public License v2 or later
 License URI: http://www.gnu.org/licenses/gpl-2.0.html
 Text Domain: akina