diff --git a/include/grpcpp/impl/codegen/message_allocator.h b/include/grpcpp/impl/codegen/message_allocator.h
index c3054313864..422f8c2ea21 100644
--- a/include/grpcpp/impl/codegen/message_allocator.h
+++ b/include/grpcpp/impl/codegen/message_allocator.h
@@ -42,8 +42,10 @@ class MessageHolder : public RpcAllocatorState {
   virtual void Release() { delete this; }
   RequestT* request() { return request_; }
   ResponseT* response() { return response_; }
+  void set_request(RequestT* request) { request_ = request; }
+  void set_response(ResponseT* response) { response_ = response; }
 
- protected:
+ private:
   // NOTE: subclasses should set these pointers.
   RequestT* request_;
   ResponseT* response_;
diff --git a/include/grpcpp/impl/codegen/server_callback.h b/include/grpcpp/impl/codegen/server_callback.h
index 62cdd452308..9254518b605 100644
--- a/include/grpcpp/impl/codegen/server_callback.h
+++ b/include/grpcpp/impl/codegen/server_callback.h
@@ -82,8 +82,8 @@ class DefaultMessageHolder
     : public experimental::MessageHolder<Request, Response> {
  public:
   DefaultMessageHolder() {
-    this->request_ = &request_obj_;
-    this->response_ = &response_obj_;
+    this->set_request(&request_obj_);
+    this->set_response(&response_obj_);
   }
   void Release() override {
     // the object is allocated in the call arena.
diff --git a/test/cpp/end2end/message_allocator_end2end_test.cc b/test/cpp/end2end/message_allocator_end2end_test.cc
index b4ed1d47f8f..2abe26fe825 100644
--- a/test/cpp/end2end/message_allocator_end2end_test.cc
+++ b/test/cpp/end2end/message_allocator_end2end_test.cc
@@ -233,24 +233,24 @@ class SimpleAllocatorTest : public MessageAllocatorEnd2endTestBase {
                         int* messages_deallocation_count)
           : request_deallocation_count_(request_deallocation_count),
             messages_deallocation_count_(messages_deallocation_count) {
-        request_ = new EchoRequest;
-        response_ = new EchoResponse;
+        set_request(new EchoRequest);
+        set_response(new EchoResponse);
       }
       void Release() override {
         (*messages_deallocation_count_)++;
-        delete request_;
-        delete response_;
+        delete request();
+        delete response();
         delete this;
       }
       void FreeRequest() override {
         (*request_deallocation_count_)++;
-        delete request_;
-        request_ = nullptr;
+        delete request();
+        set_request(nullptr);
       }
 
       EchoRequest* ReleaseRequest() {
-        auto* ret = request_;
-        request_ = nullptr;
+        auto* ret = request();
+        set_request(nullptr);
         return ret;
       }
 
@@ -341,9 +341,10 @@ class ArenaAllocatorTest : public MessageAllocatorEnd2endTestBase {
         : public experimental::MessageHolder<EchoRequest, EchoResponse> {
      public:
       MessageHolderImpl() {
-        request_ = google::protobuf::Arena::CreateMessage<EchoRequest>(&arena_);
-        response_ =
-            google::protobuf::Arena::CreateMessage<EchoResponse>(&arena_);
+        set_request(
+            google::protobuf::Arena::CreateMessage<EchoRequest>(&arena_));
+        set_response(
+            google::protobuf::Arena::CreateMessage<EchoResponse>(&arena_));
       }
       void FreeRequest() override { GPR_ASSERT(0); }