diff --git a/src/tateyama/debug/service.cpp b/src/tateyama/debug/service.cpp
index 474e9abb..fbe16cda 100644
--- a/src/tateyama/debug/service.cpp
+++ b/src/tateyama/debug/service.cpp
@@ -62,20 +62,15 @@ static void reply(google::protobuf::Message &message,
 
 static void reply_error(std::string_view error_message,
                   std::shared_ptr<tateyama::api::server::response> &res) {
-    tateyama::proto::debug::response::UnknownError error { };
     tateyama::proto::debug::response::Logging logging { };
-    error.set_message(std::string(error_message));
-    logging.set_allocated_unknown_error(&error);
+    logging.mutable_unknown_error()->set_message(std::string(error_message));
     reply(logging, res);
-    (void)logging.release_unknown_error();
 }
 
 static void success_logging(std::shared_ptr<tateyama::api::server::response> &res) {
     tateyama::proto::debug::response::Logging logging { };
-    tateyama::proto::debug::response::Void v { };
-    logging.set_allocated_success(&v);
+    (void) logging.mutable_success();
     reply(logging, res);
-    (void)logging.release_success();
 }
 
 static void command_logging(tateyama::proto::debug::request::Request &proto_req,
diff --git a/test/tateyama/debug/debug_service_test.cpp b/test/tateyama/debug/debug_service_test.cpp
index a432b248..7c6115e5 100644
--- a/test/tateyama/debug/debug_service_test.cpp
+++ b/test/tateyama/debug/debug_service_test.cpp
@@ -44,16 +44,12 @@ class debug_service_test : public ::testing::Test {
     std::string make_request(tateyama::proto::debug::request::Logging_Level level, std::string &message) {
         std::string s{};
         tateyama::proto::debug::request::Request proto_req{};
-        tateyama::proto::debug::request::Logging logging{};
-        logging.set_level(level);
-        std::string m { message };
-        logging.set_allocated_message(&m);
-        proto_req.set_allocated_logging(&logging);
+        auto* logging = proto_req.mutable_logging();
+        logging->set_level(level);
+        logging->set_message(message);
         proto_req.set_service_message_version_major(default_major);
         proto_req.set_service_message_version_minor(default_minor);
         EXPECT_TRUE(proto_req.SerializeToString(&s));
-        logging.release_message();
-        proto_req.release_logging();
         return s;
     }