diff --git a/http/http_request.hpp b/http/http_request.hpp
index 8bcce06..44ed2e3 100644
--- a/http/http_request.hpp
+++ b/http/http_request.hpp
@@ -10,6 +10,9 @@
 #include <boost/beast/websocket.hpp>
 #include <boost/url/url_view.hpp>
 
+#include <string>
+#include <string_view>
+
 namespace crow
 {
 
diff --git a/http/http_response.hpp b/http/http_response.hpp
index 7965704..72ff9e9 100644
--- a/http/http_response.hpp
+++ b/http/http_response.hpp
@@ -5,7 +5,9 @@
 #include <boost/beast/http/message.hpp>
 #include <boost/beast/http/string_body.hpp>
 
+#include <optional>
 #include <string>
+#include <string_view>
 
 namespace crow
 {