diff --git a/t-child.c b/t-child.c
index 547eb17..f4e3a04 100644
--- a/t-child.c
+++ b/t-child.c
@@ -1,74 +1,74 @@
 /* Sanity check for the process and IPC primitives.
  *
  * Copyright (C) 2016 g10 code GmbH
  *
  * This file is part of GnuPG.
  *
  * GnuPG is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 3 of the License, or
  * (at your option) any later version.
  *
  * GnuPG is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with this program; if not, see <https://www.gnu.org/licenses/>.
  */
 
 #include <errno.h>
 #include <stdio.h>
 #include <string.h>
 
 #ifdef _WIN32
 # include <fcntl.h>
 # include <io.h>
 #endif
 
 int
 main (int argc, char **argv)
 {
   char buffer[4096];
   memset (buffer, 'A', sizeof buffer);
 #if _WIN32
-  if (! setmode (stdin, O_BINARY))
+  if (! setmode (fileno (stdin), O_BINARY))
     return 23;
-  if (! setmode (stdout, O_BINARY))
+  if (! setmode (fileno (stdout), O_BINARY))
     return 23;
 #endif
 
   if (argc == 1)
     return 2;
   else if (strcmp (argv[1], "return0") == 0)
     return 0;
   else if (strcmp (argv[1], "return1") == 0)
     return 1;
   else if (strcmp (argv[1], "return77") == 0)
     return 77;
   else if (strcmp (argv[1], "hello_stdout") == 0)
     fprintf (stdout, "hello");
   else if (strcmp (argv[1], "hello_stderr") == 0)
     fprintf (stderr, "hello");
   else if (strcmp (argv[1], "stdout4096") == 0)
     fwrite (buffer, 1, sizeof buffer, stdout);
   else if (strcmp (argv[1], "stdout8192") == 0)
     {
       fwrite (buffer, 1, sizeof buffer, stdout);
       fwrite (buffer, 1, sizeof buffer, stdout);
     }
   else if (strcmp (argv[1], "cat") == 0)
     while (! feof (stdin))
       {
         size_t bytes_read;
         bytes_read = fread (buffer, 1, sizeof buffer, stdin);
         fwrite (buffer, 1, bytes_read, stdout);
       }
   else
     {
       fprintf (stderr, "unknown command %s\n", argv[1]);
       return 2;
     }
   return 0;
 }