diff --git a/map/map_loader/src/pointcloud_map_loader/differential_map_loader_module.cpp b/map/map_loader/src/pointcloud_map_loader/differential_map_loader_module.cpp
index b42b919edb59d..8322ac5f60b99 100644
--- a/map/map_loader/src/pointcloud_map_loader/differential_map_loader_module.cpp
+++ b/map/map_loader/src/pointcloud_map_loader/differential_map_loader_module.cpp
@@ -26,7 +26,7 @@ DifferentialMapLoaderModule::DifferentialMapLoaderModule(
 }
 
 void DifferentialMapLoaderModule::differentialAreaLoad(
-  const autoware_map_msgs::msg::AreaInfo area, const std::vector<std::string> & cached_ids,
+  const autoware_map_msgs::msg::AreaInfo & area, const std::vector<std::string> & cached_ids,
   GetDifferentialPointCloudMap::Response::SharedPtr & response) const
 {
   // iterate over all the available pcd map grids
@@ -52,7 +52,7 @@ void DifferentialMapLoaderModule::differentialAreaLoad(
     }
   }
 
-  for (int i = 0; i < static_cast<int>(cached_ids.size()); ++i) {
+  for (size_t i = 0; i < cached_ids.size(); ++i) {
     if (should_remove[i]) {
       response->ids_to_remove.push_back(cached_ids[i]);
     }
@@ -72,7 +72,7 @@ bool DifferentialMapLoaderModule::onServiceGetDifferentialPointCloudMap(
 
 autoware_map_msgs::msg::PointCloudMapCellWithID
 DifferentialMapLoaderModule::loadPointCloudMapCellWithID(
-  const std::string path, const std::string map_id) const
+  const std::string & path, const std::string & map_id) const
 {
   sensor_msgs::msg::PointCloud2 pcd;
   if (pcl::io::loadPCDFile(path, pcd) == -1) {
diff --git a/map/map_loader/src/pointcloud_map_loader/differential_map_loader_module.hpp b/map/map_loader/src/pointcloud_map_loader/differential_map_loader_module.hpp
index 5d6188c0b1a1f..7069e1dbdf45c 100644
--- a/map/map_loader/src/pointcloud_map_loader/differential_map_loader_module.hpp
+++ b/map/map_loader/src/pointcloud_map_loader/differential_map_loader_module.hpp
@@ -50,10 +50,10 @@ class DifferentialMapLoaderModule
     GetDifferentialPointCloudMap::Request::SharedPtr req,
     GetDifferentialPointCloudMap::Response::SharedPtr res);
   void differentialAreaLoad(
-    const autoware_map_msgs::msg::AreaInfo area_info, const std::vector<std::string> & cached_ids,
+    const autoware_map_msgs::msg::AreaInfo & area_info, const std::vector<std::string> & cached_ids,
     GetDifferentialPointCloudMap::Response::SharedPtr & response) const;
   autoware_map_msgs::msg::PointCloudMapCellWithID loadPointCloudMapCellWithID(
-    const std::string path, const std::string map_id) const;
+    const std::string & path, const std::string & map_id) const;
 };
 
 #endif  // POINTCLOUD_MAP_LOADER__DIFFERENTIAL_MAP_LOADER_MODULE_HPP_
diff --git a/map/map_loader/src/pointcloud_map_loader/partial_map_loader_module.cpp b/map/map_loader/src/pointcloud_map_loader/partial_map_loader_module.cpp
index af53438e8e321..1454b01147ac2 100644
--- a/map/map_loader/src/pointcloud_map_loader/partial_map_loader_module.cpp
+++ b/map/map_loader/src/pointcloud_map_loader/partial_map_loader_module.cpp
@@ -25,7 +25,7 @@ PartialMapLoaderModule::PartialMapLoaderModule(
 }
 
 void PartialMapLoaderModule::partialAreaLoad(
-  const autoware_map_msgs::msg::AreaInfo area,
+  const autoware_map_msgs::msg::AreaInfo & area,
   GetPartialPointCloudMap::Response::SharedPtr & response) const
 {
   // iterate over all the available pcd map grids
@@ -56,7 +56,7 @@ bool PartialMapLoaderModule::onServiceGetPartialPointCloudMap(
 }
 
 autoware_map_msgs::msg::PointCloudMapCellWithID PartialMapLoaderModule::loadPointCloudMapCellWithID(
-  const std::string path, const std::string map_id) const
+  const std::string & path, const std::string & map_id) const
 {
   sensor_msgs::msg::PointCloud2 pcd;
   if (pcl::io::loadPCDFile(path, pcd) == -1) {
diff --git a/map/map_loader/src/pointcloud_map_loader/partial_map_loader_module.hpp b/map/map_loader/src/pointcloud_map_loader/partial_map_loader_module.hpp
index 052aa4245c099..4d97ab90667ec 100644
--- a/map/map_loader/src/pointcloud_map_loader/partial_map_loader_module.hpp
+++ b/map/map_loader/src/pointcloud_map_loader/partial_map_loader_module.hpp
@@ -50,10 +50,10 @@ class PartialMapLoaderModule
     GetPartialPointCloudMap::Request::SharedPtr req,
     GetPartialPointCloudMap::Response::SharedPtr res);
   void partialAreaLoad(
-    const autoware_map_msgs::msg::AreaInfo area,
+    const autoware_map_msgs::msg::AreaInfo & area,
     GetPartialPointCloudMap::Response::SharedPtr & response) const;
   autoware_map_msgs::msg::PointCloudMapCellWithID loadPointCloudMapCellWithID(
-    const std::string path, const std::string map_id) const;
+    const std::string & path, const std::string & map_id) const;
 };
 
 #endif  // POINTCLOUD_MAP_LOADER__PARTIAL_MAP_LOADER_MODULE_HPP_
diff --git a/map/map_loader/src/pointcloud_map_loader/pointcloud_map_loader_module.cpp b/map/map_loader/src/pointcloud_map_loader/pointcloud_map_loader_module.cpp
index cd1a75fad5a03..1c67d25f08f7a 100644
--- a/map/map_loader/src/pointcloud_map_loader/pointcloud_map_loader_module.cpp
+++ b/map/map_loader/src/pointcloud_map_loader/pointcloud_map_loader_module.cpp
@@ -40,8 +40,8 @@ sensor_msgs::msg::PointCloud2 downsample(
 }
 
 PointcloudMapLoaderModule::PointcloudMapLoaderModule(
-  rclcpp::Node * node, const std::vector<std::string> & pcd_paths, const std::string publisher_name,
-  const bool use_downsample)
+  rclcpp::Node * node, const std::vector<std::string> & pcd_paths,
+  const std::string & publisher_name, const bool use_downsample)
 : logger_(node->get_logger())
 {
   rclcpp::QoS durable_qos{1};
@@ -72,12 +72,11 @@ sensor_msgs::msg::PointCloud2 PointcloudMapLoaderModule::loadPCDFiles(
   sensor_msgs::msg::PointCloud2 whole_pcd;
   sensor_msgs::msg::PointCloud2 partial_pcd;
 
-  for (int i = 0; i < static_cast<int>(pcd_paths.size()); ++i) {
+  for (size_t i = 0; i < pcd_paths.size(); ++i) {
     auto & path = pcd_paths[i];
     if (i % 50 == 0) {
       RCLCPP_INFO_STREAM(
-        logger_,
-        fmt::format("Load {} ({} out of {})", path, i + 1, static_cast<int>(pcd_paths.size())));
+        logger_, fmt::format("Load {} ({} out of {})", path, i + 1, pcd_paths.size()));
     }
 
     if (pcl::io::loadPCDFile(path, partial_pcd) == -1) {
diff --git a/map/map_loader/src/pointcloud_map_loader/pointcloud_map_loader_module.hpp b/map/map_loader/src/pointcloud_map_loader/pointcloud_map_loader_module.hpp
index 4cd0e981597c6..aebc5a17454ab 100644
--- a/map/map_loader/src/pointcloud_map_loader/pointcloud_map_loader_module.hpp
+++ b/map/map_loader/src/pointcloud_map_loader/pointcloud_map_loader_module.hpp
@@ -29,7 +29,7 @@ class PointcloudMapLoaderModule
 public:
   explicit PointcloudMapLoaderModule(
     rclcpp::Node * node, const std::vector<std::string> & pcd_paths,
-    const std::string publisher_name, const bool use_downsample);
+    const std::string & publisher_name, const bool use_downsample);
 
 private:
   rclcpp::Logger logger_;