diff --git a/src/microhttpd/mhd_send.c b/src/microhttpd/mhd_send.c
index 64079b8d..d360f981 100644
--- a/src/microhttpd/mhd_send.c
+++ b/src/microhttpd/mhd_send.c
@@ -343,7 +343,7 @@ MHD_send_on_connection2_ (struct MHD_Connection *connection,
   ret = writev (s, vector, iovcnt);
 #endif
 
-  if (ret == header_len + buffer_len)
+  if (ret == header_size + buffer_size)
     want_cork = false;
 
   post_cork_setsockopt (connection, want_cork);