diff --git a/seed/challenges/01-front-end-development-certification/basic-javascript.json b/seed/challenges/01-front-end-development-certification/basic-javascript.json
index 663456310a..bd09ac58a3 100644
--- a/seed/challenges/01-front-end-development-certification/basic-javascript.json
+++ b/seed/challenges/01-front-end-development-certification/basic-javascript.json
@@ -2794,6 +2794,7 @@
         "var testArr = [ 1,2,3,4,5];\n\nfunction nextInLine(arr, item) {\n    arr.push(item);\n    return arr.shift();\n}"
       ],
       "tests": [
+        "assert.isNumber(nextInLine([],5), 'message: <code>nextInLine([], 5)</code> should return a number.');",
         "assert(nextInLine([],1) === 1, 'message: <code>nextInLine([], 1)</code> should return <code>1</code>');",
         "assert(nextInLine([2],1) === 2, 'message: <code>nextInLine([2], 1)</code> should return <code>2</code>');",
         "assert(nextInLine([5,6,7,8,9],1) === 5, 'message: <code>nextInLine([5,6,7,8,9], 1)</code> should return <code>5</code>');",