diff --git a/src/createGridComponent.js b/src/createGridComponent.js
index fd3893e..f9d1d26 100644
--- a/src/createGridComponent.js
+++ b/src/createGridComponent.js
@@ -4,6 +4,7 @@ import memoizeOne from 'memoize-one';
 import { createElement, PureComponent } from 'react';
 import { cancelTimeout, requestTimeout } from './timer';
 import { getScrollbarSize } from './domHelpers';
+import WeakSet from './weakset';
 
 import type { TimeoutID } from './timer';
 
diff --git a/src/createListComponent.js b/src/createListComponent.js
index 5756d44..127a50b 100644
--- a/src/createListComponent.js
+++ b/src/createListComponent.js
@@ -3,6 +3,7 @@
 import memoizeOne from 'memoize-one';
 import { createElement, PureComponent } from 'react';
 import { cancelTimeout, requestTimeout } from './timer';
+import WeakSet from './weakset';
 
 import type { TimeoutID } from './timer';
 
diff --git a/src/weakset.js b/src/weakset.js
new file mode 100644
index 0000000..83a62ce
--- /dev/null
+++ b/src/weakset.js
@@ -0,0 +1,4 @@
+// @flow
+
+const WeaksetExport = typeof WeakSet === 'undefined' ? Set : WeakSet;
+export default WeaksetExport;