diff --git a/shell/platform/fuchsia/dart-pkg/zircon/sdk_ext/system.cc b/shell/platform/fuchsia/dart-pkg/zircon/sdk_ext/system.cc
index 3230b79a6b39f..1c3d642a2c987 100644
--- a/shell/platform/fuchsia/dart-pkg/zircon/sdk_ext/system.cc
+++ b/shell/platform/fuchsia/dart-pkg/zircon/sdk_ext/system.cc
@@ -423,9 +423,7 @@ struct SizedRegion {
   size_t size;
 };
 
-void System::VmoMapFinalizer(void* isolate_callback_data,
-                             Dart_WeakPersistentHandle handle,
-                             void* peer) {
+void System::VmoMapFinalizer(void* isolate_callback_data, void* peer) {
   SizedRegion* r = reinterpret_cast<SizedRegion*>(peer);
   zx_vmar_unmap(zx_vmar_root_self(), reinterpret_cast<uintptr_t>(r->region),
                 r->size);
@@ -453,9 +451,9 @@ Dart_Handle System::VmoMap(fml::RefPtr<Handle> vmo) {
   FML_DCHECK(!tonic::LogIfError(object));
 
   SizedRegion* r = new SizedRegion(data, size);
-  Dart_NewWeakPersistentHandle(object, reinterpret_cast<void*>(r),
-                               static_cast<intptr_t>(size) + sizeof(*r),
-                               System::VmoMapFinalizer);
+  Dart_NewFinalizableHandle(object, reinterpret_cast<void*>(r),
+                            static_cast<intptr_t>(size) + sizeof(*r),
+                            System::VmoMapFinalizer);
 
   return ConstructDartObject(kMapResult, ToDart(ZX_OK), object);
 }
diff --git a/shell/platform/fuchsia/dart-pkg/zircon/sdk_ext/system.h b/shell/platform/fuchsia/dart-pkg/zircon/sdk_ext/system.h
index 20540ff5d275b..3093a65b31649 100644
--- a/shell/platform/fuchsia/dart-pkg/zircon/sdk_ext/system.h
+++ b/shell/platform/fuchsia/dart-pkg/zircon/sdk_ext/system.h
@@ -69,9 +69,7 @@ class System : public fml::RefCountedThreadSafe<System>,
                                       fml::RefPtr<Handle> channel);
 
  private:
-  static void VmoMapFinalizer(void* isolate_callback_data,
-                              Dart_WeakPersistentHandle handle,
-                              void* peer);
+  static void VmoMapFinalizer(void* isolate_callback_data, void* peer);
 
   static zx::channel CloneChannelFromFileDescriptor(int fd);
 };
diff --git a/third_party/tonic/file_loader/file_loader.cc b/third_party/tonic/file_loader/file_loader.cc
index 88cc9343c76fa..32019b2de42cd 100644
--- a/third_party/tonic/file_loader/file_loader.cc
+++ b/third_party/tonic/file_loader/file_loader.cc
@@ -195,9 +195,7 @@ Dart_Handle FileLoader::Import(Dart_Handle url) {
 }
 
 namespace {
-void MallocFinalizer(void* isolate_callback_data,
-                     Dart_WeakPersistentHandle handle,
-                     void* peer) {
+void MallocFinalizer(void* isolate_callback_data, void* peer) {
   free(peer);
 }
 }  // namespace
@@ -212,7 +210,7 @@ Dart_Handle FileLoader::Kernel(Dart_Handle url) {
   }
   result =
       Dart_NewExternalTypedData(Dart_TypedData_kUint8, buffer, buffer_size);
-  Dart_NewWeakPersistentHandle(result, buffer, buffer_size, MallocFinalizer);
+  Dart_NewFinalizableHandle(result, buffer, buffer_size, MallocFinalizer);
   return result;
 }