diff --git a/src/utils/memoize.js b/src/utils/memoize.js
index e7b3bb9d7..c49bda1c7 100644
--- a/src/utils/memoize.js
+++ b/src/utils/memoize.js
@@ -1,3 +1,4 @@
+/* global Map */
 
 /**
  * The leaf node of a cache tree. Used to support variable argument length.