diff --git a/docs/CHANGELOG.md b/docs/CHANGELOG.md
index c13ca6a..de6a012 100644
--- a/docs/CHANGELOG.md
+++ b/docs/CHANGELOG.md
@@ -38,6 +38,7 @@
   command output.
 - Startup CLI help and option errors now live in a dedicated `cli_text` module
   and follow `TNT_LANG` / locale for English and Chinese users.
+- Idle-timeout disconnect notices now follow the session UI language.
 
 ### Changed
 - NORMAL mode now opens at the latest visible messages instead of the oldest
diff --git a/include/i18n.h b/include/i18n.h
index c7f1193..0021ea0 100644
--- a/include/i18n.h
+++ b/include/i18n.h
@@ -22,6 +22,7 @@ typedef enum {
     I18N_TITLE_ONLINE_FORMAT,
     I18N_TITLE_MUTED,
     I18N_TITLE_HELP_HINT,
+    I18N_IDLE_TIMEOUT_FORMAT,
     I18N_SYSTEM_USERNAME,
     I18N_SYSTEM_JOIN_FORMAT,
     I18N_SYSTEM_LEAVE_FORMAT,
diff --git a/src/i18n.c b/src/i18n.c
index 90a333c..c721a51 100644
--- a/src/i18n.c
+++ b/src/i18n.c
@@ -107,6 +107,8 @@ const char *i18n_text(help_lang_t lang, i18n_text_id_t id) {
                 return "静音";
             case I18N_TITLE_HELP_HINT:
                 return "? 帮助";
+            case I18N_IDLE_TIMEOUT_FORMAT:
+                return "\r\n\033[33m已断开: 空闲超时 (%d 分钟)\033[0m\r\n";
             case I18N_SYSTEM_USERNAME:
                 return "系统";
             case I18N_SYSTEM_JOIN_FORMAT:
@@ -237,6 +239,8 @@ const char *i18n_text(help_lang_t lang, i18n_text_id_t id) {
             return "muted";
         case I18N_TITLE_HELP_HINT:
             return "? help";
+        case I18N_IDLE_TIMEOUT_FORMAT:
+            return "\r\n\033[33mDisconnected: idle timeout (%d min)\033[0m\r\n";
         case I18N_SYSTEM_USERNAME:
             return "system";
         case I18N_SYSTEM_JOIN_FORMAT:
diff --git a/src/input.c b/src/input.c
index 441db18..458dfe0 100644
--- a/src/input.c
+++ b/src/input.c
@@ -787,7 +787,9 @@ main_loop:
 
             if (g_idle_timeout > 0 && joined_room &&
                 time(NULL) - client->last_active >= g_idle_timeout) {
-                client_printf(client, "\r\n\033[33mDisconnected: idle timeout (%d min)\033[0m\r\n",
+                client_printf(client,
+                              i18n_text(client->help_lang,
+                                        I18N_IDLE_TIMEOUT_FORMAT),
                               g_idle_timeout / 60);
                 break;
             }
diff --git a/tests/unit/test_i18n.c b/tests/unit/test_i18n.c
index ea587f6..ef98c60 100644
--- a/tests/unit/test_i18n.c
+++ b/tests/unit/test_i18n.c
@@ -82,6 +82,10 @@ TEST(text_lookup_matches_language) {
                   "online") != NULL);
     assert(strstr(i18n_text(LANG_ZH, I18N_TITLE_ONLINE_FORMAT),
                   "在线") != NULL);
+    assert(strstr(i18n_text(LANG_EN, I18N_IDLE_TIMEOUT_FORMAT),
+                  "idle timeout") != NULL);
+    assert(strstr(i18n_text(LANG_ZH, I18N_IDLE_TIMEOUT_FORMAT),
+                  "空闲超时") != NULL);
     assert(strstr(i18n_text(LANG_EN, I18N_MSG_USAGE),
                   "msg <username>") != NULL);
     assert(strstr(i18n_text(LANG_ZH, I18N_MSG_USAGE),