diff --git a/src/mfm/html-to-mfm.ts b/src/mfm/html-to-mfm.ts
index 540635036..daa228ec5 100644
--- a/src/mfm/html-to-mfm.ts
+++ b/src/mfm/html-to-mfm.ts
@@ -1,6 +1,8 @@
 const parse5 = require('parse5');
 
 export default function(html: string): string {
+	if (html == null) return null;
+
 	const dom = parse5.parseFragment(html);
 
 	let text = '';