diff --git a/packages/astro/src/vite-plugin-markdown/index.ts b/packages/astro/src/vite-plugin-markdown/index.ts
index ab0547bb23..ffaa8afc7a 100644
--- a/packages/astro/src/vite-plugin-markdown/index.ts
+++ b/packages/astro/src/vite-plugin-markdown/index.ts
@@ -167,6 +167,7 @@ ${components ? `import * from '${components}';` : ''}
 ${hasInjectedScript ? `import '${PAGE_SSR_SCRIPT_ID}';` : ''}
 ${setup}
 
+const slugger = new Slugger();
 function $$slug(value) {
 	return slugger.slug(value);
 }