diff --git a/.size-snapshot.json b/.size-snapshot.json
index 0a543a552..fddefc812 100644
--- a/.size-snapshot.json
+++ b/.size-snapshot.json
@@ -1,8 +1,8 @@
 {
   "./dist/react-big-calendar.js": {
-    "bundled": 554005,
-    "minified": 170219,
-    "gzipped": 50027
+    "bundled": 553987,
+    "minified": 170205,
+    "gzipped": 50025
   },
   "./dist/react-big-calendar.min.js": {
     "bundled": 490228,
@@ -10,9 +10,9 @@
     "gzipped": 45487
   },
   "dist/react-big-calendar.esm.js": {
-    "bundled": 169733,
-    "minified": 81582,
-    "gzipped": 20080,
+    "bundled": 169712,
+    "minified": 81562,
+    "gzipped": 20075,
     "treeshaked": {
       "rollup": {
         "code": 62970,
diff --git a/src/Popup.js b/src/Popup.js
index 56d2479f1..e5484278b 100644
--- a/src/Popup.js
+++ b/src/Popup.js
@@ -1,5 +1,5 @@
 import PropTypes from 'prop-types'
-import React, { Element } from 'react'
+import React from 'react'
 import getOffset from 'dom-helpers/query/offset'
 import getScrollTop from 'dom-helpers/query/scrollTop'
 import getScrollLeft from 'dom-helpers/query/scrollLeft'
@@ -101,7 +101,7 @@ Popup.propTypes = {
   slotEnd: PropTypes.number,
   popperRef: PropTypes.oneOfType([
     PropTypes.func,
-    PropTypes.shape({ current: PropTypes.instanceOf(Element) }),
+    PropTypes.shape({ current: PropTypes.Element }),
   ]),
 }