diff --git a/src/core/ngx_buf.h b/src/core/ngx_buf.h
index ec55ef3..d16656d 100644
--- a/src/core/ngx_buf.h
+++ b/src/core/ngx_buf.h
@@ -78,6 +78,7 @@
     ngx_chain_t                 *busy;
 
     unsigned                     sendfile;
+    unsigned                     directio;
     unsigned                     need_in_memory;
     unsigned                     need_in_temp;