diff --git a/src/os/unix/ngx_files.c b/src/os/unix/ngx_files.c
index 65d2320b2..4fdf884fc 100644
--- a/src/os/unix/ngx_files.c
+++ b/src/os/unix/ngx_files.c
@@ -246,6 +246,7 @@ ngx_write_chain_to_file(ngx_file_t *file, ngx_chain_t *cl, off_t offset,
 
         file->sys_offset += n;
         file->offset += n;
+        offset += n;
         total += n;
 
     } while (cl);