diff --git a/src/Popover.tsx b/src/Popover.tsx
index 764421c..2594214 100644
--- a/src/Popover.tsx
+++ b/src/Popover.tsx
@@ -55,7 +55,7 @@ const PopoverInternal = forwardRef(
       boundaryInset,
     });
 
-    const childRef = useRef<HTMLElement | undefined>();
+    const childRef = useRef<HTMLElement | undefined>(undefined);
 
     const [popoverState, setPopoverState] = useState<PopoverState>({
       align,
diff --git a/src/index.d.ts b/src/index.d.ts
index 92f4065..f671739 100644
--- a/src/index.d.ts
+++ b/src/index.d.ts
@@ -1,3 +1,5 @@
+import type { JSX } from 'react';
+
 export type Rect = {
   top: number;
   left: number;
diff --git a/src/useElementRef.ts b/src/useElementRef.ts
index 89f7dc9..96e42d9 100644
--- a/src/useElementRef.ts
+++ b/src/useElementRef.ts
@@ -2,7 +2,7 @@ import { useRef, useState, useLayoutEffect } from 'react';
 import { CreateContainerProps, createContainer } from './util';
 
 export const useElementRef = ({ containerClassName, containerStyle }: CreateContainerProps) => {
-  const ref = useRef<HTMLDivElement>();
+  const ref = useRef<HTMLDivElement>(undefined);
 
   const [element] = useState(() =>
     createContainer({ containerStyle, containerClassName: containerClassName }),