diff --git a/Userland/Libraries/LibWeb/HTML/Window.cpp b/Userland/Libraries/LibWeb/HTML/Window.cpp
index 7de18b1fdf4..b613ebe28fd 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();
 }
 
-DeprecatedString Window::prompt_impl(DeprecatedString const& message, DeprecatedString const& default_)
-{
-    if (auto* page = this->page())
-        return page->did_request_prompt(message, default_);
-    return {};
-}
-
 // https://html.spec.whatwg.org/multipage/timers-and-user-prompts.html#dom-settimeout
 i32 Window::set_timeout_impl(TimerHandler handler, i32 timeout, JS::MarkedVector<JS::Value> arguments)
 {
@@ -1129,7 +1122,6 @@ 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, "prompt", prompt, 0, attr);
     define_native_function(realm, "setInterval", set_interval, 1, attr);
     define_native_function(realm, "setTimeout", set_timeout, 1, attr);
     define_native_function(realm, "clearInterval", clear_interval, 1, attr);
@@ -1252,6 +1244,19 @@ bool Window::confirm(Optional<String> const& message)
     return false;
 }
 
+// https://html.spec.whatwg.org/multipage/timers-and-user-prompts.html#dom-prompt
+Optional<String> Window::prompt(Optional<String> const& message, Optional<String> const& default_)
+{
+    // FIXME: Make this fully spec compliant.
+    if (auto* page = this->page()) {
+        auto response = page->did_request_prompt(message->to_deprecated_string(), default_->to_deprecated_string());
+        if (response.is_null())
+            return {};
+        return String::from_deprecated_string(response).release_value_but_fixme_should_propagate_errors();
+    }
+    return {};
+}
+
 JS_DEFINE_NATIVE_FUNCTION(Window::open)
 {
     auto* impl = TRY(impl_from(vm));
@@ -1274,21 +1279,6 @@ 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::prompt)
-{
-    auto* impl = TRY(impl_from(vm));
-    DeprecatedString message = "";
-    DeprecatedString default_ = "";
-    if (!vm.argument(0).is_undefined())
-        message = TRY(vm.argument(0).to_deprecated_string(vm));
-    if (!vm.argument(1).is_undefined())
-        default_ = TRY(vm.argument(1).to_deprecated_string(vm));
-    auto response = impl->prompt_impl(message, default_);
-    if (response.is_null())
-        return JS::js_null();
-    return JS::PrimitiveString::create(vm, response);
-}
-
 static JS::ThrowCompletionOr<TimerHandler> make_timer_handler(JS::VM& vm, JS::Value handler)
 {
     if (handler.is_function())
diff --git a/Userland/Libraries/LibWeb/HTML/Window.h b/Userland/Libraries/LibWeb/HTML/Window.h
index d6266a962b5..b1819f22bc0 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);
-    DeprecatedString prompt_impl(DeprecatedString const&, DeprecatedString const&);
     i32 request_animation_frame_impl(WebIDL::CallbackType& js_callback);
     void cancel_animation_frame_impl(i32);
     bool has_animation_frame_callbacks() const { return m_animation_frame_callback_driver.has_callbacks(); }
@@ -144,6 +143,7 @@ public:
     // JS API functions
     void alert(String const& message = {});
     bool confirm(Optional<String> const& message);
+    Optional<String> prompt(Optional<String> const& message, Optional<String> const& default_);
 
 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(prompt);
     JS_DECLARE_NATIVE_FUNCTION(set_interval);
     JS_DECLARE_NATIVE_FUNCTION(set_timeout);
     JS_DECLARE_NATIVE_FUNCTION(clear_interval);
diff --git a/Userland/Libraries/LibWeb/HTML/Window.idl b/Userland/Libraries/LibWeb/HTML/Window.idl
index 21cfe24f835..f8f891fde74 100644
--- a/Userland/Libraries/LibWeb/HTML/Window.idl
+++ b/Userland/Libraries/LibWeb/HTML/Window.idl
@@ -8,6 +8,7 @@ interface Window : EventTarget {
     undefined alert();
     undefined alert(DOMString message);
     boolean confirm(optional DOMString message = "");
+    DOMString? prompt(optional DOMString message = "", optional DOMString default = "");
 };
 Window includes GlobalEventHandlers;
 Window includes WindowEventHandlers;