diff --git a/packages/core/src/utils/index.ts b/packages/core/src/utils/index.ts
index b740be1..6cb3611 100644
--- a/packages/core/src/utils/index.ts
+++ b/packages/core/src/utils/index.ts
@@ -61,7 +61,15 @@ const llmsTxtCache = new Map<string, string | null>()
 
 /** Fetch /llms.txt for a URL's origin. Cached per origin, `null` = tried and not found. */
 export async function fetchLlmsTxt(url: string): Promise<string | null> {
-	const origin = new URL(url).origin
+	let origin: string
+	try {
+		origin = new URL(url).origin
+	} catch {
+		return null // Invalid URL
+	}
+	// about:blank, data:, file:
+	if (origin === 'null') return null
+
 	if (llmsTxtCache.has(origin)) return llmsTxtCache.get(origin)!
 
 	const endpoint = `${origin}/llms.txt`