diff --git a/quartz/components/Comments.tsx b/quartz/components/Comments.tsx
index c5b2b391f..96e040517 100644
--- a/quartz/components/Comments.tsx
+++ b/quartz/components/Comments.tsx
@@ -39,7 +39,7 @@ export default ((opts: Options) => {
         data-input-position={opts.options.inputPosition ?? "bottom"}
         data-light-theme={opts.options.lightTheme ?? "light"}
         data-dark-theme={opts.options.darkTheme ?? "dark"}
-        data-theme-url={opts.options.themeUrl ?? `https://${cfg.baseUrl}/static/giscus`}
+        data-theme-url={opts.options.themeUrl ?? `https://${cfg.baseUrl ?? "example.com"}/static/giscus`}
       ></div>
     )
   }