diff --git a/test/built-ins/RegExp/named-groups/groups-object-subclass-sans.js b/test/built-ins/RegExp/named-groups/groups-object-subclass-sans.js
index 58a1458d81c8d303d8bdbf9bf90e087a70904894..7a69b281d8f12255dd07fe0c0d99456c36099ae5 100644
--- a/test/built-ins/RegExp/named-groups/groups-object-subclass-sans.js
+++ b/test/built-ins/RegExp/named-groups/groups-object-subclass-sans.js
@@ -27,11 +27,11 @@ class FakeRegExp extends RegExp {
 
 const re = new FakeRegExp();
 const result = re.exec("ab");
-assert.sameValue(result.__proto__, Array.prototype);
+assert.sameValue(Object.getPrototypeOf(result), Array.prototype);
 assert.sameValue(false, result.hasOwnProperty("groups"));
 
 Array.prototype.groups = { a: "b" };
-Array.prototype.groups.__proto__.b = "c";
+Object.getPrototypeOf(Array.prototype.groups).b = "c";
 assert.sameValue("b", "ab".replace(re, "$<a>"));
 assert.sameValue("c", "ab".replace(re, "$<b>"));
 Array.prototype.groups = undefined;
diff --git a/test/built-ins/RegExp/named-groups/groups-object-subclass.js b/test/built-ins/RegExp/named-groups/groups-object-subclass.js
index af5d02f28c8ec7043ab061a56eaea52aae4071c0..968e7c153ecb773a929376b0935742eb868fd369 100644
--- a/test/built-ins/RegExp/named-groups/groups-object-subclass.js
+++ b/test/built-ins/RegExp/named-groups/groups-object-subclass.js
@@ -21,14 +21,14 @@ class FakeRegExp extends RegExp {
     const fakeResult = ["ab", "a"];
     fakeResult.index = 0;
     fakeResult.groups = { a: "b" };
-    fakeResult.groups.__proto__.b = "c";
+    Object.getPrototypeOf(fakeResult.groups).b = "c";
     return fakeResult;
   }
 };
 
 const re = new FakeRegExp();
 const result = re.exec("ab");
-assert.sameValue(result.__proto__, Array.prototype);
+assert.sameValue(Object.getPrototypeOf(result), Array.prototype);
 assert(result.hasOwnProperty("groups"));
 assert.sameValue("b", result.groups.a);
 assert.sameValue("b", "ab".replace(re, "$<a>"));
diff --git a/test/built-ins/RegExp/named-groups/groups-object-undefined.js b/test/built-ins/RegExp/named-groups/groups-object-undefined.js
index 76a8fa5e6830018fd88083ff335c310761b5eee3..fea8fd0bface535a95c4fc3578f3f1c5ed9123e3 100644
--- a/test/built-ins/RegExp/named-groups/groups-object-undefined.js
+++ b/test/built-ins/RegExp/named-groups/groups-object-undefined.js
@@ -17,7 +17,7 @@ info: |
 
 const re = /./;
 const result = re.exec("a");
-assert.sameValue(result.__proto__, Array.prototype);
+assert.sameValue(Object.getPrototypeOf(result), Array.prototype);
 assert(result.hasOwnProperty("groups"));
 assert.sameValue("a", result[0]);
 assert.sameValue(0, result.index);
diff --git a/test/built-ins/RegExp/named-groups/groups-object-unmatched.js b/test/built-ins/RegExp/named-groups/groups-object-unmatched.js
index 610d205e81863680fc96f64369b3e885de3b5a86..2c7dc53c3b61d53e5c3aba6674f483331b585368 100644
--- a/test/built-ins/RegExp/named-groups/groups-object-unmatched.js
+++ b/test/built-ins/RegExp/named-groups/groups-object-unmatched.js
@@ -18,7 +18,7 @@ info: |
 
 const re = /(?<a>a).|(?<x>x)/;
 const result = re.exec("ab");
-assert.sameValue(result.__proto__, Array.prototype);
+assert.sameValue(Object.getPrototypeOf(result), Array.prototype);
 assert(result.hasOwnProperty("groups"));
 assert.sameValue("ab", result[0]);
 assert.sameValue("a", result[1]);