diff --git a/tests/test-signed-interest.cpp b/tests/test-signed-interest.cpp
index c321057..2d03097 100644
--- a/tests/test-signed-interest.cpp
+++ b/tests/test-signed-interest.cpp
@@ -11,8 +11,7 @@
 #include <iostream>
 
 using namespace std;
-using namespace ndn;
-
+namespace ndn {
 
 BOOST_AUTO_TEST_SUITE(TestSignedInterest)
 
@@ -38,3 +37,5 @@
 }
 
 BOOST_AUTO_TEST_SUITE_END()
+
+} // namespace ndn