--- a/src/os/win32/ngx_files.h
+++ b/src/os/win32/ngx_files.h
@@ -68,12 +68,14 @@ ngx_int_t ngx_file_append_mode(ngx_fd_t 
 #define ngx_close_file_n            "CloseHandle()"
 
 
-#define ngx_read_fd(fd, buf, size)  ReadFile(fd, buf, size, NULL, NULL)
+ssize_t ngx_read_fd(ngx_fd_t fd, void *buf, size_t size);
 #define ngx_read_fd_n               "ReadFile()"
 
-#define ngx_write_fd(fd, buf, size) WriteFile(fd, buf, size, NULL, NULL)
+
+ssize_t ngx_write_fd(ngx_fd_t fd, void *buf, size_t size);
 #define ngx_write_fd_n              "WriteFile()"
 
+
 #define ngx_linefeed(p)             *p++ = CR; *p++ = LF;
 #define NGX_LINEFEED_SIZE           2