diff --git a/test/language/expressions/exponentiation/exp-operator-precedence-unary-expression-semantics.js b/test/language/expressions/exponentiation/exp-operator-precedence-unary-expression-semantics.js
index 5df93dad619fdff420532f047206c2614ae99417..fc32d0ea7daa1618ceeff68b49f63935558e6279 100644
--- a/test/language/expressions/exponentiation/exp-operator-precedence-unary-expression-semantics.js
+++ b/test/language/expressions/exponentiation/exp-operator-precedence-unary-expression-semantics.js
@@ -52,6 +52,8 @@ assert.sameValue(2 ** !n, 1, "!s -> !2 -> false -> ToNumber(false) -> 0");
 
 
 var capture = [];
+var leftValue = { valueOf() { capture.push("leftValue"); return 3; }};
+var rightValue = { valueOf() { capture.push("rightValue"); return 2; }};
 
 (capture.push("left"), leftValue) ** +(capture.push("right"), rightValue);
 //                                   ^