diff --git a/Userland/Libraries/LibWeb/Streams/WritableStreamDefaultController.cpp b/Userland/Libraries/LibWeb/Streams/WritableStreamDefaultController.cpp
index 580858f4be..4bb9463c99 100644
--- a/Userland/Libraries/LibWeb/Streams/WritableStreamDefaultController.cpp
+++ b/Userland/Libraries/LibWeb/Streams/WritableStreamDefaultController.cpp
@@ -4,11 +4,21 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
+#include <LibWeb/DOM/AbortSignal.h>
 #include <LibWeb/Streams/WritableStream.h>
 #include <LibWeb/Streams/WritableStreamDefaultController.h>
 
 namespace Web::Streams {
 
+void WritableStreamDefaultController::visit_edges(Visitor& visitor)
+{
+    Base::visit_edges(visitor);
+    visitor.visit(m_signal);
+    for (auto& value : m_queue)
+        visitor.visit(value.value);
+    visitor.visit(m_stream);
+}
+
 // https://streams.spec.whatwg.org/#ws-default-controller-error
 WebIDL::ExceptionOr<void> WritableStreamDefaultController::error(JS::Value error)
 {
diff --git a/Userland/Libraries/LibWeb/Streams/WritableStreamDefaultController.h b/Userland/Libraries/LibWeb/Streams/WritableStreamDefaultController.h
index 79da393625..7b6c7fd858 100644
--- a/Userland/Libraries/LibWeb/Streams/WritableStreamDefaultController.h
+++ b/Userland/Libraries/LibWeb/Streams/WritableStreamDefaultController.h
@@ -55,6 +55,8 @@ public:
 private:
     explicit WritableStreamDefaultController(JS::Realm&);
 
+    virtual void visit_edges(Visitor&) override;
+
     // https://streams.spec.whatwg.org/#writablestreamdefaultcontroller-abortalgorithm
     // A promise-returning algorithm, taking one argument (the abort reason), which communicates a requested abort to the underlying sink
     Optional<AbortAlgorithm> m_abort_algorithm;