diff --git a/builtin_object.go b/builtin_object.go
index 764cc5f..d81edfb 100644
--- a/builtin_object.go
+++ b/builtin_object.go
@@ -144,3 +144,39 @@ func builtinObject_preventExtensions(call FunctionCall) Value {
 	}
 	return object
 }
+
+func builtinObject_isSealed(call FunctionCall) Value {
+	object := call.Argument(0)
+	if object := object._object(); object != nil {
+		if object.stash.extensible() {
+			return toValue(false)
+		}
+		result := true
+		object.enumerate(func(name string) {
+			property := object.getProperty(name)
+			if property.configurable() {
+				result = false
+			}
+		})
+		return toValue(result)
+	}
+	panic(newTypeError())
+}
+
+func builtinObject_isFrozen(call FunctionCall) Value {
+	object := call.Argument(0)
+	if object := object._object(); object != nil {
+		if object.stash.extensible() {
+			return toValue(false)
+		}
+		result := true
+		object.enumerate(func(name string) {
+			property := object.getProperty(name)
+			if property.configurable() || property.writable() {
+				result = false
+			}
+		})
+		return toValue(result)
+	}
+	panic(newTypeError())
+}
diff --git a/global.go b/global.go
index d27e611..6da6676 100644
--- a/global.go
+++ b/global.go
@@ -177,6 +177,8 @@ func newContext() *_runtime {
 		"create", 2, builtinObject_create,
 		"isExtensible", -1, builtinObject_isExtensible,
 		"preventExtensions", -1, builtinObject_preventExtensions,
+		"isSealed", -1, builtinObject_isSealed,
+		"isFrozen", -1, builtinObject_isFrozen,
 	)
 
 	self.Global.Function = self.newGlobalFunction(
diff --git a/object_test.go b/object_test.go
index 3d9b929..043b531 100644
--- a/object_test.go
+++ b/object_test.go
@@ -108,3 +108,19 @@ func TestObject_preventExtensions(t *testing.T) {
 	test(`Object.preventExtensions.length`, "1")
 	test(`Object.preventExtensions.prototype`, "undefined")
 }
+
+func TestObject_isSealed(t *testing.T) {
+	Terst(t)
+
+	test := runTest()
+	test(`Object.isSealed.length`, "1")
+	test(`Object.isSealed.prototype`, "undefined")
+}
+
+func TestObject_isFrozen(t *testing.T) {
+	Terst(t)
+
+	test := runTest()
+	test(`Object.isFrozen.length`, "1")
+	test(`Object.isFrozen.prototype`, "undefined")
+}