diff --git a/test/built-ins/Object/prototype/isPrototypeOf/S15.2.4.6_A1.js b/test/built-ins/Object/prototype/isPrototypeOf/S15.2.4.6_A1.js
deleted file mode 100644
index 5f27c33bf9..0000000000
--- a/test/built-ins/Object/prototype/isPrototypeOf/S15.2.4.6_A1.js
+++ /dev/null
@@ -1,59 +0,0 @@
-// Copyright 2009 the Sputnik authors.  All rights reserved.
-// This code is governed by the BSD license found in the LICENSE file.
-
-/*---
-info: |
-    When the isPrototypeOf method is called with argument V and when O and
-    V refer to the same object or to objects joined to each other, return true
-es5id: 15.2.4.6_A1
-description: Creating two objects with the same prototype
----*/
-
-function USER_FACTORY(name) {
-  this.name = name;
-  this.getName = function() {
-    return name;
-  };
-}
-
-
-function FORCEDUSER_FACTORY(name, grade) {
-  this.name = name;
-  this.grade = grade;
-  this.getGrade = function() {
-    return grade;
-  };
-}
-
-var proto = new USER_FACTORY("noname");
-
-FORCEDUSER_FACTORY.prototype = proto;
-
-var luke = new FORCEDUSER_FACTORY("Luke Skywalker", 12);
-//////
-// CHECK#1
-assert.sameValue(
-  proto.isPrototypeOf(luke),
-  true,
-  '#1: native ECMAScript objects have an internal property called [[Prototype]].'
-);
-
-//
-/////////
-//////
-// CHECK#2
-assert.sameValue(
-  USER_FACTORY.prototype.isPrototypeOf(luke),
-  true,
-  '#2: native ECMAScript objects have an internal property called [[Prototype]].'
-);
-
-//
-/////////
-//////
-// CHECK#3
-if (Number.isPrototypeOf(luke)) {
-  $ERROR('#2: Native ECMAScript objects have an internal property called [[Prototype]].');
-}
-//
-/////////
diff --git a/test/built-ins/Object/prototype/isPrototypeOf/S15.2.4.6_A10.js b/test/built-ins/Object/prototype/isPrototypeOf/S15.2.4.6_A10.js
deleted file mode 100644
index a1d7281691..0000000000
--- a/test/built-ins/Object/prototype/isPrototypeOf/S15.2.4.6_A10.js
+++ /dev/null
@@ -1,29 +0,0 @@
-// Copyright 2009 the Sputnik authors.  All rights reserved.
-// This code is governed by the BSD license found in the LICENSE file.
-
-/*---
-info: |
-    The Object.prototype.isPrototypeOf.length property has the attribute
-    ReadOnly
-es5id: 15.2.4.6_A10
-description: >
-    Checking if varying the Object.prototype.isPrototypeOf.length
-    property fails
-includes: [propertyHelper.js]
----*/
-
-//CHECK#1
-if (!(Object.prototype.isPrototypeOf.hasOwnProperty('length'))) {
-  $ERROR('#1: the Object.prototype.isPrototypeOf has length property');
-}
-
-var obj = Object.prototype.isPrototypeOf.length;
-
-verifyNotWritable(Object.prototype.isPrototypeOf, "length", null, function() {
-  return "shifted";
-});
-
-//CHECK#2
-if (Object.prototype.isPrototypeOf.length !== obj) {
-  $ERROR('#2: the Object.prototype.isPrototypeOf length property has the attributes ReadOnly');
-}
diff --git a/test/built-ins/Object/prototype/isPrototypeOf/S15.2.4.6_A11.js b/test/built-ins/Object/prototype/isPrototypeOf/S15.2.4.6_A11.js
deleted file mode 100644
index dcd5e13e4e..0000000000
--- a/test/built-ins/Object/prototype/isPrototypeOf/S15.2.4.6_A11.js
+++ /dev/null
@@ -1,18 +0,0 @@
-// Copyright 2009 the Sputnik authors.  All rights reserved.
-// This code is governed by the BSD license found in the LICENSE file.
-
-/*---
-info: The length property of the hasOwnProperty method is 1
-es5id: 15.2.4.6_A11
-description: Checking the Object.prototype.hasOwnProperty.length
----*/
-
-//CHECK#1
-if (!(Object.prototype.isPrototypeOf.hasOwnProperty("length"))) {
-  $ERROR('#1: the Object.prototype.isPrototypeOf has length property');
-}
-
-//CHECK#2
-if (Object.prototype.isPrototypeOf.length !== 1) {
-  $ERROR('#2: The length property of the toObject method is 1');
-}
diff --git a/test/built-ins/Object/prototype/isPrototypeOf/S15.2.4.6_A12.js b/test/built-ins/Object/prototype/isPrototypeOf/S15.2.4.6_A12.js
deleted file mode 100644
index 49afa59a15..0000000000
--- a/test/built-ins/Object/prototype/isPrototypeOf/S15.2.4.6_A12.js
+++ /dev/null
@@ -1,13 +0,0 @@
-// Copyright 2011 the Sputnik authors.  All rights reserved.
-// This code is governed by the BSD license found in the LICENSE file.
-
-/*---
-es5id: 15.2.4.6_A12
-description: >
-    Let O be the result of calling ToObject passing the this value as
-    the argument.
----*/
-
-assert.throws(TypeError, function() {
-  Object.prototype.isPrototypeOf.call(undefined, {});
-});
diff --git a/test/built-ins/Object/prototype/isPrototypeOf/S15.2.4.6_A13.js b/test/built-ins/Object/prototype/isPrototypeOf/S15.2.4.6_A13.js
deleted file mode 100644
index ebe5259a85..0000000000
--- a/test/built-ins/Object/prototype/isPrototypeOf/S15.2.4.6_A13.js
+++ /dev/null
@@ -1,13 +0,0 @@
-// Copyright 2011 the Sputnik authors.  All rights reserved.
-// This code is governed by the BSD license found in the LICENSE file.
-
-/*---
-es5id: 15.2.4.6_A13
-description: >
-    Let O be the result of calling ToObject passing the this value as
-    the argument.
----*/
-
-assert.throws(TypeError, function() {
-  Object.prototype.isPrototypeOf.call(null, {});
-});
diff --git a/test/built-ins/Object/prototype/isPrototypeOf/S15.2.4.6_A6.js b/test/built-ins/Object/prototype/isPrototypeOf/S15.2.4.6_A6.js
deleted file mode 100644
index 3ab10f971f..0000000000
--- a/test/built-ins/Object/prototype/isPrototypeOf/S15.2.4.6_A6.js
+++ /dev/null
@@ -1,16 +0,0 @@
-// Copyright 2009 the Sputnik authors.  All rights reserved.
-// This code is governed by the BSD license found in the LICENSE file.
-
-/*---
-info: Object.prototype.isPrototypeOf has not prototype property
-es5id: 15.2.4.6_A6
-description: >
-    Checking if obtaining the prototype property of
-    Object.prototype.isPrototypeOf fails
----*/
-
-//CHECK#1
-if (Object.prototype.isPrototypeOf.prototype !== undefined) {
-  $ERROR('#1: Object.prototype.isPrototypeOf has not prototype property' + Object.prototype.isPrototypeOf.prototype);
-}
-//
diff --git a/test/built-ins/Object/prototype/isPrototypeOf/S15.2.4.6_A7.js b/test/built-ins/Object/prototype/isPrototypeOf/S15.2.4.6_A7.js
deleted file mode 100644
index 5e9bf6d46f..0000000000
--- a/test/built-ins/Object/prototype/isPrototypeOf/S15.2.4.6_A7.js
+++ /dev/null
@@ -1,14 +0,0 @@
-// Copyright 2009 the Sputnik authors.  All rights reserved.
-// This code is governed by the BSD license found in the LICENSE file.
-
-/*---
-info: Object.prototype.isPrototypeOf can't be used as a constructor
-es5id: 15.2.4.6_A7
-description: Checking if creating new "Object.prototype.isPrototypeOf" fails
----*/
-
-var FACTORY = Object.prototype.isPrototypeOf;
-
-assert.throws(TypeError, function() {
-  new FACTORY;
-});
diff --git a/test/built-ins/Object/prototype/isPrototypeOf/S15.2.4.6_A8.js b/test/built-ins/Object/prototype/isPrototypeOf/S15.2.4.6_A8.js
deleted file mode 100644
index 8c959469bd..0000000000
--- a/test/built-ins/Object/prototype/isPrototypeOf/S15.2.4.6_A8.js
+++ /dev/null
@@ -1,30 +0,0 @@
-// Copyright 2009 the Sputnik authors.  All rights reserved.
-// This code is governed by the BSD license found in the LICENSE file.
-
-/*---
-info: |
-    The Object.prototype.isPrototypeOf.length property has the attribute
-    DontEnum
-es5id: 15.2.4.6_A8
-description: >
-    Checknig if enumerating the Object.prototype.isPrototypeOf.length
-    property fails
----*/
-
-//CHECK#0
-if (!(Object.prototype.isPrototypeOf.hasOwnProperty('length'))) {
-  $ERROR('#0: the Object.prototype.isPrototypeOf has length property');
-}
-
-
-// CHECK#1
-if (Object.prototype.isPrototypeOf.propertyIsEnumerable('length')) {
-  $ERROR('#1: the Object.prototype.isPrototypeOf.length property has the attributes DontEnum');
-}
-
-// CHECK#2
-for (var p in Object.prototype.isPrototypeOf) {
-  if (p === "length")
-    $ERROR('#2: the Object.prototype.isPrototypeOf.length property has the attributes DontEnum');
-}
-//
diff --git a/test/built-ins/Object/prototype/isPrototypeOf/S15.2.4.6_A9.js b/test/built-ins/Object/prototype/isPrototypeOf/S15.2.4.6_A9.js
deleted file mode 100644
index 4e9d544573..0000000000
--- a/test/built-ins/Object/prototype/isPrototypeOf/S15.2.4.6_A9.js
+++ /dev/null
@@ -1,23 +0,0 @@
-// Copyright 2009 the Sputnik authors.  All rights reserved.
-// This code is governed by the BSD license found in the LICENSE file.
-
-/*---
-info: |
-    The Object.prototype.isPrototypeOf.length property does not have the
-    attribute DontDelete
-es5id: 15.2.4.6_A9
-description: >
-    Checking deleting the Object.prototype.isPrototypeOf.length
-    property fails
----*/
-
-//CHECK#0
-if (!(Object.prototype.isPrototypeOf.hasOwnProperty('length'))) {
-  $ERROR('#0: the Object.prototype.isPrototypeOf has length property');
-}
-
-//CHECK#1
-if (!delete Object.prototype.isPrototypeOf.length) {
-  $ERROR('#1: The Object.prototype.isPrototypeOf.length property does not have the attributes DontDelete');
-}
-//
diff --git a/test/built-ins/Object/prototype/isPrototypeOf/arg-is-proxy.js b/test/built-ins/Object/prototype/isPrototypeOf/arg-is-proxy.js
new file mode 100644
index 0000000000..0b8e11dcb3
--- /dev/null
+++ b/test/built-ins/Object/prototype/isPrototypeOf/arg-is-proxy.js
@@ -0,0 +1,29 @@
+// Copyright (C) 2019 Alexey Shvayka. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-object.prototype.isprototypeof
+description: >
+  If V is a Proxy object, only its "getPrototypeOf" trap gets invoked.
+info: |
+  Object.prototype.isPrototypeOf ( V )
+
+  ...
+  3. Repeat,
+    a. Set V to ? V.[[GetPrototypeOf]]().
+    b. If V is null, return false.
+    c. If SameValue(O, V) is true, return true.
+includes: [proxyTrapsHelper.js]
+features: [Proxy]
+---*/
+
+var proxyProto = [];
+var handler = allowProxyTraps({
+  getPrototypeOf: function(_target) {
+    return proxyProto;
+  },
+});
+
+var proxy = new Proxy({}, handler);
+
+assert.sameValue(proxyProto.isPrototypeOf(proxy), true);
diff --git a/test/built-ins/Object/prototype/isPrototypeOf/builtin.js b/test/built-ins/Object/prototype/isPrototypeOf/builtin.js
new file mode 100644
index 0000000000..d81c293c21
--- /dev/null
+++ b/test/built-ins/Object/prototype/isPrototypeOf/builtin.js
@@ -0,0 +1,18 @@
+// Copyright (C) 2009 the Sputnik authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-object.prototype.isprototypeof
+description: >
+  Tests that Object.prototype.isPrototypeOf meets the requirements
+  for built-in objects defined by the introduction of chapter 17 of
+  the ECMAScript Language Specification.
+includes: [isConstructor.js]
+features: [Reflect.construct]
+---*/
+
+assert(Object.isExtensible(Object.prototype.isPrototypeOf));
+assert.sameValue(Object.prototype.toString.call(Object.prototype.isPrototypeOf), "[object Function]");
+assert.sameValue(Object.getPrototypeOf(Object.prototype.isPrototypeOf), Function.prototype);
+assert.sameValue(Object.prototype.isPrototypeOf.hasOwnProperty("prototype"), false);
+assert.sameValue(isConstructor(Object.prototype.isPrototypeOf), false);
diff --git a/test/built-ins/Object/prototype/isPrototypeOf/length.js b/test/built-ins/Object/prototype/isPrototypeOf/length.js
new file mode 100644
index 0000000000..b8e24bae8a
--- /dev/null
+++ b/test/built-ins/Object/prototype/isPrototypeOf/length.js
@@ -0,0 +1,24 @@
+// Copyright (C) 2009 the Sputnik authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-object.prototype.isprototypeof
+description: >
+  Object.prototype.isPrototypeOf.length is 1.
+info: |
+  Object.prototype.isPrototypeOf ( V )
+
+  ECMAScript Standard Built-in Objects
+
+  Unless otherwise specified, the length property of a built-in Function
+  object has the attributes { [[Writable]]: false, [[Enumerable]]: false,
+  [[Configurable]]: true }.
+includes: [propertyHelper.js]
+---*/
+
+verifyProperty(Object.prototype.isPrototypeOf, "length", {
+  value: 1,
+  writable: false,
+  enumerable: false,
+  configurable: true,
+});
diff --git a/test/built-ins/Object/prototype/isPrototypeOf/name.js b/test/built-ins/Object/prototype/isPrototypeOf/name.js
index 5459620e3f..87fca6ca11 100644
--- a/test/built-ins/Object/prototype/isPrototypeOf/name.js
+++ b/test/built-ins/Object/prototype/isPrototypeOf/name.js
@@ -2,7 +2,7 @@
 // This code is governed by the BSD license found in the LICENSE file.
 
 /*---
-es6id: 19.1.3.3
+esid: sec-object.prototype.isprototypeof
 description: >
   Object.prototype.isPrototypeOf.name is "isPrototypeOf".
 info: |
@@ -19,8 +19,9 @@ info: |
 includes: [propertyHelper.js]
 ---*/
 
-assert.sameValue(Object.prototype.isPrototypeOf.name, "isPrototypeOf");
-
-verifyNotEnumerable(Object.prototype.isPrototypeOf, "name");
-verifyNotWritable(Object.prototype.isPrototypeOf, "name");
-verifyConfigurable(Object.prototype.isPrototypeOf, "name");
+verifyProperty(Object.prototype.isPrototypeOf, "name", {
+  value: "isPrototypeOf",
+  writable: false,
+  enumerable: false,
+  configurable: true,
+});
diff --git a/test/built-ins/Object/prototype/isPrototypeOf/null-this-and-object-arg-throws.js b/test/built-ins/Object/prototype/isPrototypeOf/null-this-and-object-arg-throws.js
new file mode 100644
index 0000000000..11f0acaabb
--- /dev/null
+++ b/test/built-ins/Object/prototype/isPrototypeOf/null-this-and-object-arg-throws.js
@@ -0,0 +1,19 @@
+// Copyright (C) 2011 the Sputnik authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-object.prototype.isprototypeof
+description: >
+  The ordering of steps 1 and 2 preserves the behaviour specified by previous
+  editions of this specification for the case where V is not an object and
+  the this value is undefined or null.
+info: |
+  Object.prototype.isPrototypeOf ( V )
+
+  1. If Type(V) is not Object, return false.
+  2. Let O be ? ToObject(this value).
+---*/
+
+assert.throws(TypeError, function() {
+  Object.prototype.isPrototypeOf.call(null, function() {});
+});
diff --git a/test/built-ins/Object/prototype/isPrototypeOf/null-this-and-primitive-arg-returns-false.js b/test/built-ins/Object/prototype/isPrototypeOf/null-this-and-primitive-arg-returns-false.js
new file mode 100644
index 0000000000..1f440e9388
--- /dev/null
+++ b/test/built-ins/Object/prototype/isPrototypeOf/null-this-and-primitive-arg-returns-false.js
@@ -0,0 +1,23 @@
+// Copyright (C) 2019 Alexey Shvayka. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-object.prototype.isprototypeof
+description: >
+  The ordering of steps 1 and 2 preserves the behaviour specified by previous
+  editions of this specification for the case where V is not an object and
+  the this value is undefined or null.
+info: |
+  Object.prototype.isPrototypeOf ( V )
+
+  1. If Type(V) is not Object, return false.
+  2. Let O be ? ToObject(this value).
+features: [Symbol]
+---*/
+
+assert.sameValue(Object.prototype.isPrototypeOf.call(null, undefined), false);
+assert.sameValue(Object.prototype.isPrototypeOf.call(null, null), false);
+assert.sameValue(Object.prototype.isPrototypeOf.call(null, false), false);
+assert.sameValue(Object.prototype.isPrototypeOf.call(null, ""), false);
+assert.sameValue(Object.prototype.isPrototypeOf.call(null, Symbol()), false);
+assert.sameValue(Object.prototype.isPrototypeOf.call(null, 10), false);
diff --git a/test/built-ins/Object/prototype/isPrototypeOf/this-value-is-in-prototype-chain-of-arg.js b/test/built-ins/Object/prototype/isPrototypeOf/this-value-is-in-prototype-chain-of-arg.js
new file mode 100644
index 0000000000..373bb49bbb
--- /dev/null
+++ b/test/built-ins/Object/prototype/isPrototypeOf/this-value-is-in-prototype-chain-of-arg.js
@@ -0,0 +1,42 @@
+// Copyright (C) 2009 the Sputnik authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-object.prototype.isprototypeof
+description: >
+  Object.prototype.isPrototypeOf returns true if either parameter V
+  and O refer to the same object or O is in [[Prototype]] chain of V.
+info: |
+  Object.prototype.isPrototypeOf ( V )
+
+  ...
+  3. Repeat,
+    a. Set V to ? V.[[GetPrototypeOf]]().
+    b. If V is null, return false.
+    c. If SameValue(O, V) is true, return true.
+---*/
+
+function USER_FACTORY(name) {
+  this.name = name;
+  this.getName = function() {
+    return name;
+  };
+}
+
+function FORCEDUSER_FACTORY(name, grade) {
+  this.name = name;
+  this.grade = grade;
+  this.getGrade = function() {
+    return grade;
+  };
+}
+
+var proto = new USER_FACTORY("noname");
+
+FORCEDUSER_FACTORY.prototype = proto;
+
+var luke = new FORCEDUSER_FACTORY("Luke Skywalker", 12);
+
+assert.sameValue(proto.isPrototypeOf(luke), true);
+assert.sameValue(USER_FACTORY.prototype.isPrototypeOf(luke), true);
+assert.sameValue(Number.isPrototypeOf(luke), false);
diff --git a/test/built-ins/Object/prototype/isPrototypeOf/undefined-this-and-object-arg-throws.js b/test/built-ins/Object/prototype/isPrototypeOf/undefined-this-and-object-arg-throws.js
new file mode 100644
index 0000000000..75294d9f0c
--- /dev/null
+++ b/test/built-ins/Object/prototype/isPrototypeOf/undefined-this-and-object-arg-throws.js
@@ -0,0 +1,19 @@
+// Copyright (C) 2011 the Sputnik authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-object.prototype.isprototypeof
+description: >
+  The ordering of steps 1 and 2 preserves the behaviour specified by previous
+  editions of this specification for the case where V is not an object and
+  the this value is undefined or null.
+info: |
+  Object.prototype.isPrototypeOf ( V )
+
+  1. If Type(V) is not Object, return false.
+  2. Let O be ? ToObject(this value).
+---*/
+
+assert.throws(TypeError, function() {
+  Object.prototype.isPrototypeOf.call(undefined, {});
+});
diff --git a/test/built-ins/Object/prototype/isPrototypeOf/undefined-this-and-primitive-arg-returns-false.js b/test/built-ins/Object/prototype/isPrototypeOf/undefined-this-and-primitive-arg-returns-false.js
new file mode 100644
index 0000000000..3aa0f3e573
--- /dev/null
+++ b/test/built-ins/Object/prototype/isPrototypeOf/undefined-this-and-primitive-arg-returns-false.js
@@ -0,0 +1,23 @@
+// Copyright (C) 2019 Alexey Shvayka. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-object.prototype.isprototypeof
+description: >
+  The ordering of steps 1 and 2 preserves the behaviour specified by previous
+  editions of this specification for the case where V is not an object and
+  the this value is undefined or null.
+info: |
+  Object.prototype.isPrototypeOf ( V )
+
+  1. If Type(V) is not Object, return false.
+  2. Let O be ? ToObject(this value).
+features: [Symbol]
+---*/
+
+assert.sameValue(Object.prototype.isPrototypeOf.call(undefined, undefined), false);
+assert.sameValue(Object.prototype.isPrototypeOf.call(undefined, null), false);
+assert.sameValue(Object.prototype.isPrototypeOf.call(undefined, true), false);
+assert.sameValue(Object.prototype.isPrototypeOf.call(undefined, "str"), false);
+assert.sameValue(Object.prototype.isPrototypeOf.call(undefined, Symbol("desc")), false);
+assert.sameValue(Object.prototype.isPrototypeOf.call(undefined, 3.14), false);