diff --git a/packages/docusaurus/src/client/exports/Link.tsx b/packages/docusaurus/src/client/exports/Link.tsx
index 76c9f4f5ea69..e294ecff7b70 100644
--- a/packages/docusaurus/src/client/exports/Link.tsx
+++ b/packages/docusaurus/src/client/exports/Link.tsx
@@ -100,7 +100,7 @@ function Link(
 
   const IOSupported = ExecutionEnvironment.canUseIntersectionObserver;
 
-  const ioRef = useRef<IntersectionObserver>();
+  const ioRef = useRef<IntersectionObserver>(undefined);
 
   const handleRef = (el: HTMLAnchorElement | null) => {
     innerRef.current = el;