diff --git a/quartz/cfg.ts b/quartz/cfg.ts
index 12d3e3457..1e8f96e9f 100644
--- a/quartz/cfg.ts
+++ b/quartz/cfg.ts
@@ -63,7 +63,7 @@ export interface GlobalConfiguration {
   /** Glob patterns to not search */
   ignorePatterns: string[]
   /** Glob patterns to mark files as unlisted (hidden from listings but still accessible via direct link) */
-  unlistedPatterns?: string[]
+  unlistedPatterns: string[]
   /** Whether to use created, modified, or published as the default type of date */
   defaultDateType: ValidDateType
   /** Base URL to use for CNAME files, sitemaps, and RSS feeds that require an absolute URL.