diff --git a/src/easy_http/EasyHttp.h b/src/easy_http/EasyHttp.h
index 3b930c5..e41d8f5 100644
--- a/src/easy_http/EasyHttp.h
+++ b/src/easy_http/EasyHttp.h
@@ -4,6 +4,7 @@
 #include "EasyHttpOptionsBuilder.h"
 #include <async++.h>
 #include <vector>
+#include <optional>
 
 namespace ezhttp
 {
diff --git a/src/easy_http/EasyHttpInterface.h b/src/easy_http/EasyHttpInterface.h
index db2a3b1..b7ac91d 100644
--- a/src/easy_http/EasyHttpInterface.h
+++ b/src/easy_http/EasyHttpInterface.h
@@ -3,6 +3,7 @@
 #include "cpr/cpr.h"
 #include <functional>
 #include <utility>
+#include <optional>
 
 namespace ezhttp
 {
@@ -50,4 +51,4 @@ namespace ezhttp
         virtual std::shared_ptr<RequestControl> SendRequest(RequestMethod method, const cpr::Url &url, const RequestOptions &options, const RequestCallback& on_complete) = 0;
         virtual void RunFrame() = 0;
     };
-}
\ No newline at end of file
+}