diff --git a/src/lib/markdown.ts b/src/lib/markdown.ts
index 0f8ebf0..cc0da34 100644
--- a/src/lib/markdown.ts
+++ b/src/lib/markdown.ts
@@ -4,6 +4,31 @@ import { createHighlighter, type Highlighter } from 'shiki'
 
 let highlighter: Highlighter | null = null
 
+const allowed_langs = [
+  'python',
+  'javascript',
+  'typescript',
+  'typst',
+  'markdown',
+  'json',
+  'toml',
+  'yaml',
+  'bash',
+  'c',
+  'c++',
+  'rust',
+  'go',
+  'zig',
+  'makefile',
+  'make',
+  'nim',
+  'nix',
+  'kdl',
+  'md',
+  'sh',
+  'mermaid',
+]
+
 /**
  * Markdown 渲染函数。
  *
@@ -14,29 +39,7 @@ export async function renderMarkdown(content: string): Promise<string> {
     highlighter = await createHighlighter({
       themes: ['one-light', 'one-dark-pro'],
       /* 额...要我自己定义需要的所有语言吗 */
-      langs: [
-        'python',
-        'javascript',
-        'typescript',
-        'typst',
-        'markdown',
-        'json',
-        'toml',
-        'yaml',
-        'bash',
-        'c',
-        'c++',
-        'rust',
-        'go',
-        'zig',
-        'makefile',
-        'make',
-        'nim',
-        'nix',
-        'kdl',
-        'md',
-        'sh',
-      ],
+      langs: allowed_langs,
     })
   }
 
@@ -45,7 +48,7 @@ export async function renderMarkdown(content: string): Promise<string> {
     linkify: true,
     highlight: (code, lang) => {
       return highlighter!.codeToHtml(code, {
-        lang: lang || 'text',
+        lang: allowed_langs.indexOf(lang) != -1 ? lang : 'text',
         themes: {
           light: 'one-light',
           dark: 'one-dark-pro',