diff --git a/src/util/backports.hpp b/src/util/backports.hpp
index 072d1c7..acb03e6 100644
--- a/src/util/backports.hpp
+++ b/src/util/backports.hpp
@@ -35,7 +35,7 @@
 #if __cpp_lib_make_unique
 using std::make_unique;
 #else
-template<typename T, typename... Args>
+template<typename T, typename ...Args>
 inline unique_ptr<T>
 make_unique(Args&&... args)
 {
@@ -74,4 +74,6 @@
 
 } // namespace ndn
 
+#include "backports-optional.hpp"
+
 #endif // NDN_UTIL_BACKPORTS_HPP