diff --git a/test/language/expressions/object/method-definition/async-super-call-body.js b/test/language/expressions/object/method-definition/async-super-call-body.js
index 40459314f634c57995d16049198818173dbd4f7b..f01679307017cc2c24a015ab60b5eaf409ed3ce3 100644
--- a/test/language/expressions/object/method-definition/async-super-call-body.js
+++ b/test/language/expressions/object/method-definition/async-super-call-body.js
@@ -16,11 +16,12 @@ var sup = {
 }
 
 var child = {
-  __proto__: sup,
   async method() {
     var x = await super.method();
     assert.sameValue(x, 'sup');
   }
 }
 
+Object.setPrototypeOf(child, sup);
+
 child.method().then($DONE, $DONE);
diff --git a/test/language/expressions/object/method-definition/async-super-call-param.js b/test/language/expressions/object/method-definition/async-super-call-param.js
index 5eb55b18cf4fbf0c3b38cf1e550bcfe222d9cfc0..ed290d76c2d8bedb8f11f18b71e71042d7d55e43 100644
--- a/test/language/expressions/object/method-definition/async-super-call-param.js
+++ b/test/language/expressions/object/method-definition/async-super-call-param.js
@@ -16,12 +16,13 @@ var sup = {
 }
 
 var child = {
-  __proto__: sup,
   async method(x = super.method()) {
     var y = await x;
     assert.sameValue(y, 'sup');
   }
 }
 
+Object.setPrototypeOf(child, sup);
+
 child.method().then($DONE, $DONE);