diff --git a/hpb/BUILD b/hpb/BUILD
index 98a6761914..ad97ba8562 100644
--- a/hpb/BUILD
+++ b/hpb/BUILD
@@ -95,6 +95,7 @@ cc_library(
         "@abseil-cpp//absl/strings",
     ] + select({
         ":hpb_backend_cpp": [
+            "//hpb/backend/cpp:repeated_field",
         ],
         ":hpb_backend_upb": [
             "//hpb/backend/upb:repeated_field",
diff --git a/hpb/backend/BUILD b/hpb/backend/BUILD
index b05ba2f061..fc615dd4dc 100644
--- a/hpb/backend/BUILD
+++ b/hpb/backend/BUILD
@@ -17,6 +17,7 @@ cc_library(
         "//hpb:multibackend",
     ] + select({
         "//hpb:hpb_backend_cpp": [
+            "//hpb/backend/cpp:error",
             "//src/google/protobuf:arena",
         ],
         "//hpb:hpb_backend_upb": [
diff --git a/hpb/backend/cpp/BUILD b/hpb/backend/cpp/BUILD
index 1bee930040..35a94e6116 100644
--- a/hpb/backend/cpp/BUILD
+++ b/hpb/backend/cpp/BUILD
@@ -5,6 +5,7 @@
 # license that can be found in the LICENSE file or at
 # https://developers.google.com/open-source/licenses/bsd
 
+load("@rules_cc//cc:cc_test.bzl", "cc_test")
 load("@rules_cc//cc:defs.bzl", "cc_library")
 
 package(default_applicable_licenses = ["//:license"])
@@ -30,3 +31,28 @@ cc_library(
         "//hpb/internal",
     ],
 )
+
+cc_library(
+    name = "error",
+    hdrs = ["error.h"],
+    visibility = ["//hpb:__subpackages__"],
+)
+
+cc_library(
+    name = "repeated_field",
+    hdrs = ["repeated_field.h"],
+    visibility = ["//hpb:__subpackages__"],
+)
+
+cc_test(
+    name = "cpp_test",
+    srcs = ["cpp_test.cc"],
+    deps = [
+        "//hpb",
+        "//hpb:arena",
+        "//hpb:ptr",
+        "//hpb_generator/tests:test_model_hpb_proto",
+        "@googletest//:gtest",
+        "@googletest//:gtest_main",
+    ],
+)
diff --git a/hpb/backend/cpp/cpp.h b/hpb/backend/cpp/cpp.h
index e7288c8bf1..58ea8f466f 100644
--- a/hpb/backend/cpp/cpp.h
+++ b/hpb/backend/cpp/cpp.h
@@ -20,12 +20,12 @@ namespace hpb::internal::backend::cpp {
 // hpb(cpp) backend stubs.
 
 template <typename T>
-typename T::Proxy CreateMessage(Arena& arena) {
+typename T::Proxy CreateMessage(hpb::Arena& arena) {
   return typename T::Proxy();
 }
 
 template <typename T>
-typename T::Proxy CloneMessage(Ptr<T> message, Arena& arena) {
+typename T::Proxy CloneMessage(Ptr<T> message, hpb::Arena& arena) {
   abort();
 }
 
@@ -40,7 +40,7 @@ void DeepCopy(Ptr<const T> source_message, Ptr<T> target_message) {
 }
 
 template <typename T>
-absl::string_view Serialize(PtrOrRaw<T> message, Arena& arena) {
+absl::string_view Serialize(PtrOrRaw<T> message, hpb::Arena& arena) {
   abort();
 }
 
diff --git a/hpb/backend/cpp/cpp_test.cc b/hpb/backend/cpp/cpp_test.cc
new file mode 100644
index 0000000000..6500249cd8
--- /dev/null
+++ b/hpb/backend/cpp/cpp_test.cc
@@ -0,0 +1,25 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2025 Google LLC.  All rights reserved.
+//
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file or at
+// https://developers.google.com/open-source/licenses/bsd
+
+#include <gtest/gtest.h>
+#include "hpb_generator/tests/test_model.hpb.h"
+#include "hpb/arena.h"
+#include "hpb/hpb.h"
+#include "hpb/ptr.h"
+
+namespace hpb::testing {
+namespace {
+
+using ::hpb_unittest::protos::TestModel;
+
+TEST(CppBackend, CanCreateMessage) {
+  hpb::Arena arena;
+  hpb::Ptr<TestModel> test_model_ptr = hpb::CreateMessage<TestModel>(arena);
+  (void)test_model_ptr;
+}
+}  // namespace
+}  // namespace hpb::testing
diff --git a/hpb/backend/cpp/error.h b/hpb/backend/cpp/error.h
new file mode 100644
index 0000000000..2475ae2750
--- /dev/null
+++ b/hpb/backend/cpp/error.h
@@ -0,0 +1,21 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2025 Google LLC.  All rights reserved.
+//
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file or at
+// https://developers.google.com/open-source/licenses/bsd
+
+#ifndef GOOGLE_PROTOBUF_HPB_BACKEND_CPP_ERROR_H__
+#define GOOGLE_PROTOBUF_HPB_BACKEND_CPP_ERROR_H__
+
+namespace hpb {
+namespace internal {
+namespace backend {
+namespace cpp {
+class Error {};
+}  // namespace cpp
+}  // namespace backend
+}  // namespace internal
+}  // namespace hpb
+
+#endif  // GOOGLE_PROTOBUF_HPB_BACKEND_CPP_ERROR_H__
diff --git a/hpb/backend/cpp/repeated_field.h b/hpb/backend/cpp/repeated_field.h
new file mode 100644
index 0000000000..d76e4fbef4
--- /dev/null
+++ b/hpb/backend/cpp/repeated_field.h
@@ -0,0 +1,24 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2025 Google LLC.  All rights reserved.
+//
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file or at
+// https://developers.google.com/open-source/licenses/bsd
+
+#ifndef GOOGLE_PROTOBUF_HPB_BACKEND_CPP_REPEATED_FIELD_H__
+#define GOOGLE_PROTOBUF_HPB_BACKEND_CPP_REPEATED_FIELD_H__
+
+namespace hpb::internal {
+
+template <typename T>
+class RepeatedFieldScalarProxy {};
+
+template <typename T>
+class RepeatedFieldStringProxy {};
+
+template <typename T>
+class RepeatedFieldProxy {};
+
+}  // namespace hpb::internal
+
+#endif  // GOOGLE_PROTOBUF_HPB_BACKEND_CPP_REPEATED_FIELD_H__
diff --git a/hpb/backend/types.h b/hpb/backend/types.h
index f1b023e4a0..1bae6a8883 100644
--- a/hpb/backend/types.h
+++ b/hpb/backend/types.h
@@ -14,6 +14,7 @@
 #include "upb/mem/arena.hpp"
 #elif HPB_INTERNAL_BACKEND == HPB_INTERNAL_BACKEND_CPP
 #include "google/protobuf/arena.h"
+#include "hpb/backend/cpp/error.h"
 #endif
 
 namespace hpb {
@@ -25,6 +26,7 @@ namespace upb {
 using Arena = ::upb::Arena;
 }
 #elif HPB_INTERNAL_BACKEND == HPB_INTERNAL_BACKEND_CPP
+using Error = ::hpb::internal::backend::cpp::Error;
 namespace cpp {
 using Arena = google::protobuf::Arena;
 }
diff --git a/hpb/extension.cc b/hpb/extension.cc
index da3d4a9f54..d0270f3893 100644
--- a/hpb/extension.cc
+++ b/hpb/extension.cc
@@ -7,6 +7,9 @@
 
 #include "hpb/extension.h"
 
+#include "hpb/multibackend.h"
+
+#if HPB_INTERNAL_BACKEND == HPB_INTERNAL_BACKEND_UPB
 #include "upb/mini_table/extension_registry.h"
 
 namespace hpb {
@@ -15,6 +18,6 @@ upb_ExtensionRegistry* GetUpbExtensions(
     const ExtensionRegistry& extension_registry) {
   return extension_registry.registry_;
 }
-
 }  // namespace internal
 }  // namespace hpb
+#endif
diff --git a/hpb/hpb.h b/hpb/hpb.h
index 5171810e89..c79f6252e3 100644
--- a/hpb/hpb.h
+++ b/hpb/hpb.h
@@ -64,6 +64,13 @@ void ClearMessage(internal::PtrOrRawMutable<T> message) {
   backend::ClearMessage(message);
 }
 
+// Note that the default extension registry is the the generated registry.
+template <typename T>
+hpb::StatusOr<T> Parse(absl::string_view bytes, ParseOptions options) {
+  return backend::Parse<T>(bytes, options);
+}
+
+#if HPB_INTERNAL_BACKEND == HPB_INTERNAL_BACKEND_UPB
 template <typename T>
 ABSL_MUST_USE_RESULT bool Parse(internal::PtrOrRaw<T> message,
                                 absl::string_view bytes,
@@ -72,11 +79,6 @@ ABSL_MUST_USE_RESULT bool Parse(internal::PtrOrRaw<T> message,
   return backend::Parse(message, bytes, extension_registry);
 }
 
-// Note that the default extension registry is the the generated registry.
-template <typename T>
-hpb::StatusOr<T> Parse(absl::string_view bytes, ParseOptions options) {
-  return backend::Parse<T>(bytes, options);
-}
 
 // Deprecated. Use the overload that returns hpb::StatusOr<T> instead.
 // Note that the default extension registry is the empty registry.
@@ -87,6 +89,7 @@ absl::StatusOr<T> Parse(absl::string_view bytes,
                             ExtensionRegistry::empty_registry()) {
   return backend::Parse<T>(bytes, extension_registry);
 }
+#endif
 
 template <typename T>
 absl::StatusOr<absl::string_view> Serialize(internal::PtrOrRaw<T> message,
diff --git a/hpb/repeated_field.h b/hpb/repeated_field.h
index b452bf8e03..de67268b8d 100644
--- a/hpb/repeated_field.h
+++ b/hpb/repeated_field.h
@@ -18,6 +18,10 @@
 
 #if HPB_INTERNAL_BACKEND == HPB_INTERNAL_BACKEND_UPB
 #include "hpb/backend/upb/repeated_field.h"
+#elif HPB_INTERNAL_BACKEND == HPB_INTERNAL_BACKEND_CPP
+#include "hpb/backend/cpp/repeated_field.h"
+#else
+#error "Unsupported backend"
 #endif
 
 namespace hpb {
diff --git a/hpb_generator/generator.cc b/hpb_generator/generator.cc
index bd7507136d..f534ade711 100644
--- a/hpb_generator/generator.cc
+++ b/hpb_generator/generator.cc
@@ -65,6 +65,8 @@ void WriteHeader(const google::protobuf::FileDescriptor* file, Context& ctx) {
                                                                {{".", "::"}}),
                                            "::protos")}},
                R"cc(
+#include "hpb/internal/internal.h"
+
                  // message stubs
                  namespace $namespace$ {