diff --git a/Userland/Libraries/LibWeb/HTML/HTMLIFrameElement.cpp b/Userland/Libraries/LibWeb/HTML/HTMLIFrameElement.cpp
index 9123744716..05b43a1a6f 100644
--- a/Userland/Libraries/LibWeb/HTML/HTMLIFrameElement.cpp
+++ b/Userland/Libraries/LibWeb/HTML/HTMLIFrameElement.cpp
@@ -61,11 +61,11 @@ void HTMLIFrameElement::inserted()
     // When an iframe element element is inserted into a document whose browsing context is non-null, the user agent must run these steps:
     if (in_a_document_tree() && document().browsing_context()) {
         // 1. Create a new child navigable for element.
-        MUST(create_new_child_navigable([this] {
+        MUST(create_new_child_navigable(JS::create_heap_function(realm().heap(), [this] {
             // 3. Process the iframe attributes for element, with initialInsertion set to true.
             process_the_iframe_attributes(true);
             set_content_navigable_initialized();
-        }));
+        })));
 
         // FIXME: 2. If element has a sandbox attribute, then parse the sandboxing directive given the attribute's value and element's iframe sandboxing flag set.
     }
diff --git a/Userland/Libraries/LibWeb/HTML/NavigableContainer.cpp b/Userland/Libraries/LibWeb/HTML/NavigableContainer.cpp
index a6cb701efa..efe4b3bcf9 100644
--- a/Userland/Libraries/LibWeb/HTML/NavigableContainer.cpp
+++ b/Userland/Libraries/LibWeb/HTML/NavigableContainer.cpp
@@ -59,7 +59,7 @@ JS::GCPtr<NavigableContainer> NavigableContainer::navigable_container_with_conte
 }
 
 // https://html.spec.whatwg.org/multipage/document-sequences.html#create-a-new-child-navigable
-WebIDL::ExceptionOr<void> NavigableContainer::create_new_child_navigable(JS::SafeFunction<void()> afterSessionHistoryUpdate)
+WebIDL::ExceptionOr<void> NavigableContainer::create_new_child_navigable(JS::Handle<JS::HeapFunction<void()>> after_session_history_update)
 {
     // 1. Let parentNavigable be element's node navigable.
     auto parent_navigable = navigable();
@@ -110,7 +110,7 @@ WebIDL::ExceptionOr<void> NavigableContainer::create_new_child_navigable(JS::Saf
     auto traversable = parent_navigable->traversable_navigable();
 
     // 12. Append the following session history traversal steps to traversable:
-    traversable->append_session_history_traversal_steps([traversable, navigable, parent_navigable, history_entry, afterSessionHistoryUpdate = move(afterSessionHistoryUpdate)] {
+    traversable->append_session_history_traversal_steps([traversable, navigable, parent_navigable, history_entry, after_session_history_update = move(after_session_history_update)] {
         // 1. Let parentDocState be parentNavigable's active session history entry's document state.
         auto parent_doc_state = parent_navigable->active_session_history_entry()->document_state();
 
@@ -137,8 +137,8 @@ WebIDL::ExceptionOr<void> NavigableContainer::create_new_child_navigable(JS::Saf
         // 7. Update for navigable creation/destruction given traversable
         traversable->update_for_navigable_creation_or_destruction();
 
-        if (afterSessionHistoryUpdate) {
-            afterSessionHistoryUpdate();
+        if (after_session_history_update) {
+            after_session_history_update->function()();
         }
     });
 
diff --git a/Userland/Libraries/LibWeb/HTML/NavigableContainer.h b/Userland/Libraries/LibWeb/HTML/NavigableContainer.h
index 0fa07ff385..e0cbbeb2b9 100644
--- a/Userland/Libraries/LibWeb/HTML/NavigableContainer.h
+++ b/Userland/Libraries/LibWeb/HTML/NavigableContainer.h
@@ -64,7 +64,7 @@ protected:
     // https://html.spec.whatwg.org/multipage/iframe-embed-object.html#navigate-an-iframe-or-frame
     void navigate_an_iframe_or_frame(URL::URL url, ReferrerPolicy::ReferrerPolicy referrer_policy, Optional<String> srcdoc_string = {});
 
-    WebIDL::ExceptionOr<void> create_new_child_navigable(JS::SafeFunction<void()> afterSessionHistoryUpdate = {});
+    WebIDL::ExceptionOr<void> create_new_child_navigable(JS::Handle<JS::HeapFunction<void()>> after_session_history_update = {});
 
     // https://html.spec.whatwg.org/multipage/document-sequences.html#content-navigable
     JS::GCPtr<Navigable> m_content_navigable { nullptr };