diff --git a/http/http_response.hpp b/http/http_response.hpp
index 81c664a..cbffdfc 100644
--- a/http/http_response.hpp
+++ b/http/http_response.hpp
@@ -259,7 +259,7 @@
         }
 
         size_t hashval = std::hash<nlohmann::json>{}(jsonValue);
-        return "\"" + intToHexString(hashval, 8) + "\"";
+        return std::format("\"{:08X}\"", hashval);
     }
 
     void write(std::string&& bodyPart)