diff --git a/src/security/certificate-extension.cpp b/src/security/certificate-extension.cpp
index e3ceff6..69a2d10 100644
--- a/src/security/certificate-extension.cpp
+++ b/src/security/certificate-extension.cpp
@@ -55,4 +55,4 @@
   extension.MessageEnd();
 }
  
-}
+} // namespace ndn