diff --git a/runtime/flutter_runner/vulkan_surface.h b/runtime/flutter_runner/vulkan_surface.h
index f79091c..ff866b5 100644
--- a/runtime/flutter_runner/vulkan_surface.h
+++ b/runtime/flutter_runner/vulkan_surface.h
@@ -194,8 +194,7 @@
   size_t age_ = 0;
   bool valid_ = false;
 
-  flutter::LayerRasterCacheKey retained_key_ =
-      {nullptr, SkMatrix::MakeScale(1, 1)};
+  flutter::LayerRasterCacheKey retained_key_ = {0, SkMatrix::MakeScale(1, 1)};
   std::unique_ptr<scenic::EntityNode> retained_node_ = nullptr;
 
   std::atomic<bool> used_in_retained_rendering_ = false;
diff --git a/runtime/flutter_runner/vulkan_surface_pool.cc b/runtime/flutter_runner/vulkan_surface_pool.cc
index 4bb076f..bd547d1 100644
--- a/runtime/flutter_runner/vulkan_surface_pool.cc
+++ b/runtime/flutter_runner/vulkan_surface_pool.cc
@@ -124,9 +124,9 @@
 
   const flutter::LayerRasterCacheKey& retained_key =
       vulkan_surface->GetRetainedKey();
-  if (retained_key.id() != nullptr) {
-    // Add the surface to |retained_surfaces_| if its retained key has a non-
-    // null layer (|retained_key.id()|).
+  if (retained_key.id() != 0) {
+    // Add the surface to |retained_surfaces_| if its retained key has a valid
+    // layer id (|retained_key.id()|).
     //
     // We have to add the entry to |retained_surfaces_| map early when it's
     // still pending (|is_pending| = true). Otherwise (if we add the surface