diff --git a/CHANGELOG b/CHANGELOG
index 83ad13f02..fbc3ee042 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -10,6 +10,7 @@ CHANGELOG RoundCube Webmail
 - Fix SMTP test in Installer (#1486952)
 - Fix "Select all" causes message to be opened in folder with exactly one message (#1486913)
 - Fix Tab key doesn't work in HTML editor in Google Chrome (#1486925)
+- Fix TinyMCE uses zh_CN when zh_TW locale is set (#1486929)
 
 RELEASE 0.4
 -----------
diff --git a/program/include/main.inc b/program/include/main.inc
index f9ce5476e..fa5534f10 100644
--- a/program/include/main.inc
+++ b/program/include/main.inc
@@ -1505,7 +1505,11 @@ function rcube_html_editor($mode='')
   if ($hook['abort'])
     return;  
 
-  $lang = strtolower(substr($_SESSION['language'], 0, 2));
+  $lang = strtolower($_SESSION['language']);
+
+  // TinyMCE uses 'tw' for zh_TW (which is wrong, because tw is a code of Twi language)
+  $lang = ($lang == 'zh_tw') ? 'tw' : substr($lang, 0, 2);
+
   if (!file_exists(INSTALL_PATH . 'program/js/tiny_mce/langs/'.$lang.'.js'))
     $lang = 'en';