diff --git a/curriculum/challenges/english/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/arguments-optional.md b/curriculum/challenges/english/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/arguments-optional.md
index a92d047cd6d..9b1c2e3eee6 100644
--- a/curriculum/challenges/english/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/arguments-optional.md
+++ b/curriculum/challenges/english/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/arguments-optional.md
@@ -66,6 +66,12 @@ assert.isUndefined(addTogether(2)([3]));
 assert.isUndefined(addTogether('2', 3));
 ```
 
+`addTogether(5, undefined)` should return `undefined`.
+
+```js
+assert.isUndefined(addTogether(5, undefined));
+```
+
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