diff --git a/http/utility.hpp b/http/utility.hpp
index 0a61f3f..be50636 100644
--- a/http/utility.hpp
+++ b/http/utility.hpp
@@ -4,6 +4,7 @@
 
 #include <openssl/crypto.h>
 
+#include <chrono>
 #include <cstdint>
 #include <cstring>
 #include <functional>