diff --git a/Userland/Libraries/LibWeb/Animations/Animation.cpp b/Userland/Libraries/LibWeb/Animations/Animation.cpp
index 625f038e8f..4902b92bf1 100644
--- a/Userland/Libraries/LibWeb/Animations/Animation.cpp
+++ b/Userland/Libraries/LibWeb/Animations/Animation.cpp
@@ -21,21 +21,19 @@ namespace Web::Animations {
 JS_DEFINE_ALLOCATOR(Animation);
 
 // https://www.w3.org/TR/web-animations-1/#dom-animation-animation
-JS::NonnullGCPtr<Animation> Animation::create(JS::Realm& realm, JS::GCPtr<AnimationEffect> effect, JS::GCPtr<AnimationTimeline> timeline)
+JS::NonnullGCPtr<Animation> Animation::create(JS::Realm& realm, JS::GCPtr<AnimationEffect> effect, Optional<JS::GCPtr<AnimationTimeline>> timeline)
 {
-    auto& vm = realm.vm();
-
     // 1. Let animation be a new Animation object.
     auto animation = realm.heap().allocate<Animation>(realm, realm);
 
     // 2. Run the procedure to set the timeline of an animation on animation passing timeline as the new timeline or, if
     //    a timeline argument is missing, passing the default document timeline of the Document associated with the
     //    Window that is the current global object.
-    if (vm.argument_count() < 2) {
+    if (!timeline.has_value()) {
         auto& window = verify_cast<HTML::Window>(HTML::current_global_object());
         timeline = window.associated_document().timeline();
     }
-    animation->set_timeline(timeline);
+    animation->set_timeline(timeline.release_value());
 
     // 3. Run the procedure to set the associated effect of an animation on animation passing source as the new effect.
     animation->set_effect(effect);
@@ -43,7 +41,7 @@ JS::NonnullGCPtr<Animation> Animation::create(JS::Realm& realm, JS::GCPtr<Animat
     return animation;
 }
 
-WebIDL::ExceptionOr<JS::NonnullGCPtr<Animation>> Animation::construct_impl(JS::Realm& realm, JS::GCPtr<AnimationEffect> effect, JS::GCPtr<AnimationTimeline> timeline)
+WebIDL::ExceptionOr<JS::NonnullGCPtr<Animation>> Animation::construct_impl(JS::Realm& realm, JS::GCPtr<AnimationEffect> effect, Optional<JS::GCPtr<AnimationTimeline>> timeline)
 {
     return create(realm, effect, timeline);
 }
diff --git a/Userland/Libraries/LibWeb/Animations/Animation.h b/Userland/Libraries/LibWeb/Animations/Animation.h
index b514f70b4b..212d87fe16 100644
--- a/Userland/Libraries/LibWeb/Animations/Animation.h
+++ b/Userland/Libraries/LibWeb/Animations/Animation.h
@@ -18,8 +18,8 @@ class Animation : public DOM::EventTarget {
     JS_DECLARE_ALLOCATOR(Animation);
 
 public:
-    static JS::NonnullGCPtr<Animation> create(JS::Realm&, JS::GCPtr<AnimationEffect>, JS::GCPtr<AnimationTimeline>);
-    static WebIDL::ExceptionOr<JS::NonnullGCPtr<Animation>> construct_impl(JS::Realm&, JS::GCPtr<AnimationEffect>, JS::GCPtr<AnimationTimeline>);
+    static JS::NonnullGCPtr<Animation> create(JS::Realm&, JS::GCPtr<AnimationEffect>, Optional<JS::GCPtr<AnimationTimeline>>);
+    static WebIDL::ExceptionOr<JS::NonnullGCPtr<Animation>> construct_impl(JS::Realm&, JS::GCPtr<AnimationEffect>, Optional<JS::GCPtr<AnimationTimeline>>);
 
     FlyString const& id() const { return m_id; }
     void set_id(FlyString value) { m_id = move(value); }
diff --git a/Userland/Libraries/LibWeb/Animations/Animation.idl b/Userland/Libraries/LibWeb/Animations/Animation.idl
index 6df833c909..23c4fe1bf1 100644
--- a/Userland/Libraries/LibWeb/Animations/Animation.idl
+++ b/Userland/Libraries/LibWeb/Animations/Animation.idl
@@ -6,7 +6,7 @@
 [Exposed=Window]
 interface Animation : EventTarget {
     constructor(optional AnimationEffect? effect = null,
-                optional AnimationTimeline? timeline);
+                [ExplicitNull] optional AnimationTimeline? timeline);
 
     attribute DOMString id;
     attribute AnimationEffect? effect;