diff --git a/include/sdbusplus/asio/connection.hpp b/include/sdbusplus/asio/connection.hpp
index 7e7cac0..57504c1 100644
--- a/include/sdbusplus/asio/connection.hpp
+++ b/include/sdbusplus/asio/connection.hpp
@@ -37,6 +37,7 @@
 #include <sdbusplus/utility/type_traits.hpp>
 
 #include <chrono>
+#include <functional>
 #include <string>
 #include <tuple>