diff --git a/http/http_client.hpp b/http/http_client.hpp
index fe5ef8e..1568b25 100644
--- a/http/http_client.hpp
+++ b/http/http_client.hpp
@@ -503,7 +503,7 @@
                   const boost::beast::http::fields& httpHeader,
                   const boost::beast::http::verb verb,
                   const RetryPolicyData& retryPolicy,
-                  std::function<void(Response&)>& resHandler)
+                  const std::function<void(Response&)>& resHandler)
     {
         std::weak_ptr<ConnectionPool> weakSelf = weak_from_this();
 
@@ -674,7 +674,7 @@
                               const boost::beast::http::fields& httpHeader,
                               const boost::beast::http::verb verb,
                               const std::string& retryPolicyName,
-                              std::function<void(Response&)>& resHandler)
+                              const std::function<void(Response&)>& resHandler)
     {
         std::string clientKey = destIP + ":" + std::to_string(destPort);
         // Use nullptr to avoid creating a ConnectionPool each time