diff --git a/httplib.h b/httplib.h
index ba6e666..047b3e9 100644
--- a/httplib.h
+++ b/httplib.h
@@ -7646,7 +7646,7 @@ inline bool ClientImpl::process_request(Stream &strm, Request &req,
 inline ContentProviderWithoutLength ClientImpl::get_multipart_content_provider(
     const std::string &boundary, const MultipartFormDataItems &items,
     const MultipartFormDataProviderItems &provider_items) const {
-  size_t cur_item = 0;
+  const size_t cur_item = 0;
   size_t cur_start = 0;
   // cur_item and cur_start are copied to within the std::function and maintain
   // state between successive calls