diff --git a/include/http_utility.hpp b/include/http_utility.hpp
index e1a8e2a..cf3ddc2 100644
--- a/include/http_utility.hpp
+++ b/include/http_utility.hpp
@@ -41,8 +41,9 @@
     {"text/html", ContentType::HTML},
 }};
 
-inline ContentType getPreferedContentType(std::string_view header,
-                                          std::span<ContentType> preferedOrder)
+inline ContentType
+    getPreferedContentType(std::string_view header,
+                           std::span<const ContentType> preferedOrder)
 {
     size_t lastIndex = 0;
     while (lastIndex < header.size() + 1)