diff --git a/src/nlsr_adjacent.hpp b/src/nlsr_adjacent.hpp
index 910b8a9..86a6cf5 100644
--- a/src/nlsr_adjacent.hpp
+++ b/src/nlsr_adjacent.hpp
@@ -1,6 +1,8 @@
 #ifndef ADJACENT_HPP
 #define ADJACENT_HPP
 
+namespace nlsr {
+
 using namespace std;
 
 class Adjacent{
@@ -78,4 +80,6 @@
 std::ostream&
 operator << (std::ostream &os, Adjacent &adj);
 
+} // namespace nlsr
+
 #endif