diff --git a/src/identity-challenge/challenge-module.hpp b/src/identity-challenge/challenge-module.hpp
index 66f705e..eabb19d 100644
--- a/src/identity-challenge/challenge-module.hpp
+++ b/src/identity-challenge/challenge-module.hpp
@@ -21,7 +21,7 @@
 #ifndef NDNCERT_CHALLENGE_MODULE_HPP
 #define NDNCERT_CHALLENGE_MODULE_HPP
 
-#include "ca-state.hpp"
+#include "ca-detail/ca-state.hpp"
 
 namespace ndn {
 namespace ndncert {