diff --git a/l10n/zh-CN/viewer.properties b/l10n/zh-CN/viewer.properties
index 7ab0cd239..80ee751b6 100644
--- a/l10n/zh-CN/viewer.properties
+++ b/l10n/zh-CN/viewer.properties
@@ -44,8 +44,8 @@ bookmark_label=当前视图
 # Tooltips and alt text for side panel toolbar buttons
 # (the _label strings are alt text for the buttons, the .title strings are
 # tooltips)
-toggle_slider.title=切换侧栏
-toggle_slider_label=切换侧栏
+toggle_sidebar.title=切换侧栏
+toggle_sidebar_label=切换侧栏
 outline.title=显示文档大纲
 outline_label=文档大纲
 thumbs.title=显示缩略图
@@ -111,6 +111,7 @@ page_scale_actual=实际大小
 loading_error_indicator=错误
 loading_error=加载 PDF 文件时出错。
 invalid_file_error=PDF 文件无效或已损坏。
+missing_file_error=缺失 PDF 文件。
 
 # LOCALIZATION NOTE (text_annotation_type): This is used as a tooltip.
 # "{{type}}" will be replaced with an annotation type from a list defined in