diff --git a/packages/client/setup/monaco.ts b/packages/client/setup/monaco.ts
index 05f480521f..4119e57389 100644
--- a/packages/client/setup/monaco.ts
+++ b/packages/client/setup/monaco.ts
@@ -92,7 +92,7 @@ const setup = createSingletonPromise(async () => {
   monaco.languages.register({ id: 'typescript' })
   monaco.languages.register({ id: 'javascript' })
 
-  const { shiki, themes, shikiToMonaco } = await import('#slidev/shiki')
+  const { shiki, langs, themes, shikiToMonaco } = await import('#slidev/shiki')
   const highlighter = await shiki
 
   const editorOptions: MonacoSetupReturn['editorOptions'] & object = {}
@@ -113,6 +113,10 @@ const setup = createSingletonPromise(async () => {
         : themes.light || 'vitesse-light')
     })
   }
+  // Register all languages, otherwise Monaco will not highlight them
+  for (const lang of langs) {
+    monaco.languages.register({ id: lang })
+  }
 
   return {
     monaco,