diff --git a/http/common.hpp b/http/common.hpp
index 6f6b24c..01e90b2 100644
--- a/http/common.hpp
+++ b/http/common.hpp
@@ -48,7 +48,7 @@
             std::cerr << i << ", ";
         }
         std::cerr << std::endl;
-        for (auto& i : stringParams)
+        for (const std::string& i : stringParams)
         {
             std::cerr << i << ", ";
         }