diff --git a/Userland/Libraries/LibWeb/HTML/Window.cpp b/Userland/Libraries/LibWeb/HTML/Window.cpp
index 0142ae02d1..7de18b1fdf 100644
--- a/Userland/Libraries/LibWeb/HTML/Window.cpp
+++ b/Userland/Libraries/LibWeb/HTML/Window.cpp
@@ -430,13 +430,6 @@ WebIDL::ExceptionOr<JS::GCPtr<HTML::WindowProxy>> Window::open_impl(StringView u
     return target_browsing_context->window_proxy();
 }
 
-bool Window::confirm_impl(DeprecatedString const& message)
-{
-    if (auto* page = this->page())
-        return page->did_request_confirm(message);
-    return false;
-}
-
 DeprecatedString Window::prompt_impl(DeprecatedString const& message, DeprecatedString const& default_)
 {
     if (auto* page = this->page())
@@ -1136,7 +1129,6 @@ WebIDL::ExceptionOr<void> Window::initialize_web_interfaces(Badge<WindowEnvironm
     define_native_accessor(realm, "devicePixelRatio", device_pixel_ratio_getter, {}, JS::Attribute::Enumerable | JS::Attribute::Configurable);
     u8 attr = JS::Attribute::Writable | JS::Attribute::Enumerable | JS::Attribute::Configurable;
     define_native_function(realm, "open", open, 0, attr);
-    define_native_function(realm, "confirm", confirm, 0, attr);
     define_native_function(realm, "prompt", prompt, 0, attr);
     define_native_function(realm, "setInterval", set_interval, 1, attr);
     define_native_function(realm, "setTimeout", set_timeout, 1, attr);
@@ -1250,6 +1242,16 @@ void Window::alert(String const& message)
         page->did_request_alert(message.to_deprecated_string());
 }
 
+// https://html.spec.whatwg.org/multipage/timers-and-user-prompts.html#dom-confirm
+bool Window::confirm(Optional<String> const& message)
+{
+    // FIXME: Make this fully spec compliant.
+    // NOTE: `message` has an IDL-provided default value and is never empty.
+    if (auto* page = this->page())
+        return page->did_request_confirm(message->to_deprecated_string());
+    return false;
+}
+
 JS_DEFINE_NATIVE_FUNCTION(Window::open)
 {
     auto* impl = TRY(impl_from(vm));
@@ -1272,15 +1274,6 @@ JS_DEFINE_NATIVE_FUNCTION(Window::open)
     return TRY(Bindings::throw_dom_exception_if_needed(vm, [&] { return impl->open_impl(url, target, features); }));
 }
 
-JS_DEFINE_NATIVE_FUNCTION(Window::confirm)
-{
-    auto* impl = TRY(impl_from(vm));
-    DeprecatedString message = "";
-    if (!vm.argument(0).is_undefined())
-        message = TRY(vm.argument(0).to_deprecated_string(vm));
-    return JS::Value(impl->confirm_impl(message));
-}
-
 JS_DEFINE_NATIVE_FUNCTION(Window::prompt)
 {
     auto* impl = TRY(impl_from(vm));
diff --git a/Userland/Libraries/LibWeb/HTML/Window.h b/Userland/Libraries/LibWeb/HTML/Window.h
index 40b5c498f6..d6266a962b 100644
--- a/Userland/Libraries/LibWeb/HTML/Window.h
+++ b/Userland/Libraries/LibWeb/HTML/Window.h
@@ -66,7 +66,6 @@ public:
     void set_import_maps_allowed(bool import_maps_allowed) { m_import_maps_allowed = import_maps_allowed; }
 
     WebIDL::ExceptionOr<JS::GCPtr<HTML::WindowProxy>> open_impl(StringView url, StringView target, StringView features);
-    bool confirm_impl(DeprecatedString const&);
     DeprecatedString prompt_impl(DeprecatedString const&, DeprecatedString const&);
     i32 request_animation_frame_impl(WebIDL::CallbackType& js_callback);
     void cancel_animation_frame_impl(i32);
@@ -144,6 +143,7 @@ public:
 
     // JS API functions
     void alert(String const& message = {});
+    bool confirm(Optional<String> const& message);
 
 private:
     explicit Window(JS::Realm&);
@@ -267,7 +267,6 @@ private:
     JS_DECLARE_NATIVE_FUNCTION(is_secure_context_getter);
 
     JS_DECLARE_NATIVE_FUNCTION(open);
-    JS_DECLARE_NATIVE_FUNCTION(confirm);
     JS_DECLARE_NATIVE_FUNCTION(prompt);
     JS_DECLARE_NATIVE_FUNCTION(set_interval);
     JS_DECLARE_NATIVE_FUNCTION(set_timeout);
diff --git a/Userland/Libraries/LibWeb/HTML/Window.idl b/Userland/Libraries/LibWeb/HTML/Window.idl
index 67bc7da2f4..21cfe24f83 100644
--- a/Userland/Libraries/LibWeb/HTML/Window.idl
+++ b/Userland/Libraries/LibWeb/HTML/Window.idl
@@ -7,6 +7,7 @@ interface Window : EventTarget {
     // user prompts
     undefined alert();
     undefined alert(DOMString message);
+    boolean confirm(optional DOMString message = "");
 };
 Window includes GlobalEventHandlers;
 Window includes WindowEventHandlers;