diff --git a/src/nlsr_conf_param.cpp b/src/nlsr_conf_param.cpp
index 8ae7647..1e2fc64 100644
--- a/src/nlsr_conf_param.cpp
+++ b/src/nlsr_conf_param.cpp
@@ -1,6 +1,8 @@
 #include<iostream>
 #include "nlsr_conf_param.hpp"
 
+namespace nlsr {
+
 using namespace std;
 
 ostream&
@@ -25,3 +27,5 @@
 
 	return os;
 }
+
+} //namespace nlsr