diff --git a/quartz/cfg.ts b/quartz/cfg.ts
index 8d1334ca1..9e93fd141 100644
--- a/quartz/cfg.ts
+++ b/quartz/cfg.ts
@@ -41,7 +41,7 @@ export type Analytics =
 
 export interface GlobalConfiguration {
   pageTitle: string
-  pageTitleSuffix: string
+  pageTitleSuffix?: string
   /** Whether to enable single-page-app style rendering. this prevents flashes of unstyled content and improves smoothness of Quartz */
   enableSPA: boolean
   /** Whether to display Wikipedia-style popovers when hovering over links */