diff --git a/src/notion-to-md.ts b/src/notion-to-md.ts
index cb2a7be..e87d311 100644
--- a/src/notion-to-md.ts
+++ b/src/notion-to-md.ts
@@ -142,7 +142,7 @@ export class NotionToMarkdown {
             nestingLevel,
           );
 
-          const formattedContent = (mdstr.parent ?? mdstr[pageIdentifier])
+          const formattedContent = (mdstr.parent ?? mdstr[pageIdentifier] ?? '')
             .split("\n")
             .map((line) => (line.trim() ? `> ${line}` : ">"))
             .join("\n")