diff --git a/Userland/Libraries/LibWeb/HTML/Window.cpp b/Userland/Libraries/LibWeb/HTML/Window.cpp
index 2b4e97ddd8..403951ead2 100644
--- a/Userland/Libraries/LibWeb/HTML/Window.cpp
+++ b/Userland/Libraries/LibWeb/HTML/Window.cpp
@@ -1073,7 +1073,6 @@ WebIDL::ExceptionOr<void> Window::initialize_web_interfaces(Badge<WindowEnvironm
     MUST_OR_THROW_OOM(Bindings::WindowGlobalMixin::initialize(realm, *this));
 
     // FIXME: These should be native accessors, not properties
-    define_native_accessor(realm, "top", top_getter, nullptr, JS::Attribute::Enumerable);
     define_native_accessor(realm, "parent", parent_getter, {}, JS::Attribute::Enumerable);
     define_native_accessor(realm, "frameElement", frame_element_getter, {}, JS::Attribute::Enumerable);
     define_native_accessor(realm, "performance", performance_getter, performance_setter, JS::Attribute::Enumerable | JS::Attribute::Configurable);
@@ -1251,6 +1250,18 @@ u32 Window::length() const
     return static_cast<u32>(document_tree_child_browsing_context_count());
 }
 
+// https://html.spec.whatwg.org/multipage/nav-history-apis.html#dom-top
+JS::GCPtr<WindowProxy const> Window::top() const
+{
+    // 1. If this's navigable is null, then return null.
+    auto const* browsing_context = this->browsing_context();
+    if (!browsing_context)
+        return {};
+
+    // 2. Return this's navigable's top-level traversable's active WindowProxy.
+    return browsing_context->top_level_browsing_context().window_proxy();
+}
+
 // https://html.spec.whatwg.org/multipage/system-state.html#dom-navigator
 JS::NonnullGCPtr<Navigator> Window::navigator() const
 {
@@ -1548,20 +1559,6 @@ size_t Window::document_tree_child_browsing_context_count() const
     return this_browsing_context->document_tree_child_browsing_context_count();
 }
 
-// https://html.spec.whatwg.org/multipage/browsers.html#dom-top
-JS_DEFINE_NATIVE_FUNCTION(Window::top_getter)
-{
-    auto* impl = TRY(impl_from(vm));
-
-    // 1. If this Window object's browsing context is null, then return null.
-    auto* browsing_context = impl->browsing_context();
-    if (!browsing_context)
-        return JS::js_null();
-
-    // 2. Return this Window object's browsing context's top-level browsing context's WindowProxy object.
-    return browsing_context->top_level_browsing_context().window_proxy();
-}
-
 JS_DEFINE_NATIVE_FUNCTION(Window::parent_getter)
 {
     auto* impl = TRY(impl_from(vm));
diff --git a/Userland/Libraries/LibWeb/HTML/Window.h b/Userland/Libraries/LibWeb/HTML/Window.h
index e6774cbf68..e75db1c3bd 100644
--- a/Userland/Libraries/LibWeb/HTML/Window.h
+++ b/Userland/Libraries/LibWeb/HTML/Window.h
@@ -147,6 +147,7 @@ public:
 
     JS::NonnullGCPtr<WindowProxy> frames() const;
     u32 length() const;
+    JS::GCPtr<WindowProxy const> top() const;
 
     JS::NonnullGCPtr<Navigator> navigator() const;
 
@@ -218,8 +219,6 @@ public:
     CrossOriginPropertyDescriptorMap& cross_origin_property_descriptor_map() { return m_cross_origin_property_descriptor_map; }
 
 private:
-    JS_DECLARE_NATIVE_FUNCTION(top_getter);
-
     JS_DECLARE_NATIVE_FUNCTION(frame_element_getter);
 
     JS_DECLARE_NATIVE_FUNCTION(location_setter);
diff --git a/Userland/Libraries/LibWeb/HTML/Window.idl b/Userland/Libraries/LibWeb/HTML/Window.idl
index 250ba9014e..b589298c79 100644
--- a/Userland/Libraries/LibWeb/HTML/Window.idl
+++ b/Userland/Libraries/LibWeb/HTML/Window.idl
@@ -17,6 +17,7 @@ interface Window : EventTarget {
     // other browsing contexts
     [Replaceable] readonly attribute WindowProxy frames;
     [Replaceable] readonly attribute unsigned long length;
+    [LegacyUnforgeable] readonly attribute WindowProxy? top;
 
     // the user agent
     readonly attribute Navigator navigator;