diff --git a/system_metrics_collector/src/system_metrics_collector/linux_process_memory_measurement_node.cpp b/system_metrics_collector/src/system_metrics_collector/linux_process_memory_measurement_node.cpp
index 189bf60e..f6c70fef 100644
--- a/system_metrics_collector/src/system_metrics_collector/linux_process_memory_measurement_node.cpp
+++ b/system_metrics_collector/src/system_metrics_collector/linux_process_memory_measurement_node.cpp
@@ -28,6 +28,10 @@
 namespace
 {
 
+constexpr const char PROC[] = "/proc/";
+constexpr const char STATM[] = "/statm";
+constexpr const char METRIC_NAME[] = "_memory_percent_used";
+
 /**
  * Return the total system memory.
  *
diff --git a/system_metrics_collector/src/system_metrics_collector/linux_process_memory_measurement_node.hpp b/system_metrics_collector/src/system_metrics_collector/linux_process_memory_measurement_node.hpp
index 45b03200..476b7cc6 100644
--- a/system_metrics_collector/src/system_metrics_collector/linux_process_memory_measurement_node.hpp
+++ b/system_metrics_collector/src/system_metrics_collector/linux_process_memory_measurement_node.hpp
@@ -25,12 +25,6 @@
 #include "rclcpp/rclcpp.hpp"
 #include "rcutils/logging_macros.h"
 
-namespace
-{
-constexpr const char PROC[] = "/proc/";
-constexpr const char STATM[] = "/statm";
-constexpr const char METRIC_NAME[] = "_memory_percent_used";
-}  // namespace
 
 namespace system_metrics_collector
 {