diff --git a/snippets/chainAsync.md b/snippets/chainAsync.md
index bc6ca1b37..2ad3efee3 100644
--- a/snippets/chainAsync.md
+++ b/snippets/chainAsync.md
@@ -6,10 +6,11 @@ Loop through an array of functions containing asynchronous events, calling `next
 
 ```js
 const chainAsync = fns => {
-  let curr = 0, last = fns[fns.length - 1];
+  let curr = 0;
+  const last = fns[fns.length - 1];
   const next = () => {
     const fn = fns[curr++]
-    fn(fn === last ? null : next)
+    fn === last ? fn(undefined) : fn(next);
   }
   next();
 };
diff --git a/test/chainAsync.test.js b/test/chainAsync.test.js
index 44da9fef4..4a01542c5 100644
--- a/test/chainAsync.test.js
+++ b/test/chainAsync.test.js
@@ -28,7 +28,7 @@ test('Last function does not receive "next" argument', () => {
       next();
     },
     next => {
-      expect(next).toBe(null);
+      expect(next).toBe(undefined);
     }
   ]);
 });