diff --git a/curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-data-structures/check-for-the-presence-of-an-element-with-indexof.english.md b/curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-data-structures/check-for-the-presence-of-an-element-with-indexof.english.md
index 69a84ba1091..dc6110c0d9e 100644
--- a/curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-data-structures/check-for-the-presence-of-an-element-with-indexof.english.md
+++ b/curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-data-structures/check-for-the-presence-of-an-element-with-indexof.english.md
@@ -31,6 +31,8 @@ fruits.indexOf('pears'); // returns 1, the first index at which the element exis
 
 ```yml
 tests:
+  - text: The <code>quickCheck</code> function should return a boolean (<code>true</code> or <code>false</code>), not a string (<code>"true"</code> or <code>"false"</code>)
+    testString: assert.isBoolean(quickCheck(['squash', 'onions', 'shallots'], 'mushrooms'));
   - text: <code>quickCheck(["squash", "onions", "shallots"], "mushrooms")</code> should return <code>false</code>
     testString: assert.strictEqual(quickCheck(['squash', 'onions', 'shallots'], 'mushrooms'), false);
   - text: <code>quickCheck(["onions", "squash", "shallots"], "onions")</code> should return <code>true</code>