diff --git a/src/render.ts b/src/render.ts
index 1f44369..b104d76 100644
--- a/src/render.ts
+++ b/src/render.ts
@@ -48,7 +48,7 @@ export function link(
   opts?: { title?: string; external?: boolean },
 ): string {
   if (opts?.external) {
-    return `<a href="${url instanceof URL ? url.href : url}" title="${opts?.title}" target="_blank">${text}</a>`;
+    return `<a href="${url instanceof URL ? url.href : url}" title="${opts?.title ?? ''}" target="_blank">${text}</a>`;
   }
 
   return `[${text || url}](${url || "#"}${opts?.title ? ` "${opts.title}"` : ""})`;