diff --git a/src/face.hpp b/src/face.hpp
index 47e841e..a42a95f 100644
--- a/src/face.hpp
+++ b/src/face.hpp
@@ -41,12 +41,16 @@
 namespace ndn {
 
 class Transport;
-class KeyChain;
 
 class PendingInterestId;
 class RegisteredPrefixId;
 class InterestFilterId;
 
+namespace security {
+class KeyChain;
+}
+using security::KeyChain;
+
 namespace nfd {
 class Controller;
 }