diff --git a/src/nlsr_npt.cpp b/src/nlsr_npt.cpp
index 01b98e5..498b2ca 100644
--- a/src/nlsr_npt.cpp
+++ b/src/nlsr_npt.cpp
@@ -6,6 +6,8 @@
 #include "nlsr_npte.hpp"
 #include "nlsr.hpp"
 
+namespace nlsr {
+
 using namespace std;
 
 static bool
@@ -138,3 +140,5 @@
 		cout <<(*it)<<endl;
 	}
 }
+
+}