diff --git a/include/cinatra/utils.hpp b/include/cinatra/utils.hpp
index 277a7d62..8e7bdd83 100644
--- a/include/cinatra/utils.hpp
+++ b/include/cinatra/utils.hpp
@@ -10,6 +10,7 @@
 #include <array>
 #include <asio/buffer.hpp>
 #include <cctype>
+#include <charconv>
 #include <cstddef>  //std::byte
 #include <cstdlib>
 #include <iomanip>