diff --git a/src/microhttpd/mhd_send.h b/src/microhttpd/mhd_send.h
index 3d440b84..1b2ad6a3 100644
--- a/src/microhttpd/mhd_send.h
+++ b/src/microhttpd/mhd_send.h
@@ -156,7 +156,7 @@ MHD_connection_set_cork_state_ (struct MHD_Connection *connection,
  */
 ssize_t
 MHD_send_iovec_ (struct MHD_Connection *connection,
-                 struct MHD_iovec_track_ *r_iov,
+                 struct MHD_iovec_track_ *const r_iov,
                  bool push_data);