--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,11 @@
 2011-09-20  Bruno Haible  <bruno@clisp.org>
 
+	fseeko tests: EBADF tests.
+	* tests/test-fseeko4.sh: New file.
+	* tests/test-fseeko4.c: New file.
+	* modules/fseeko-tests (Files): Add them.
+	(Makefile.am): Arrange to compile test-fseeko4 and run test-fseeko4.sh.
+
 	Tests for function fputc().
 	* modules/fputc-tests: New file.
 	* tests/test-fputc.c: New file.

--- a/modules/fseeko-tests
+++ b/modules/fseeko-tests
@@ -4,6 +4,8 @@
 tests/test-fseeko2.sh
 tests/test-fseeko3.c
 tests/test-fseeko3.sh
+tests/test-fseeko4.c
+tests/test-fseeko4.sh
 tests/signature.h
 tests/macros.h
 m4/ungetc.m4
@@ -14,5 +16,5 @@
 gl_FUNC_UNGETC_WORKS
 
 Makefile.am:
-TESTS += test-fseeko.sh test-fseeko2.sh test-fseeko3.sh
-check_PROGRAMS += test-fseeko test-fseeko3
+TESTS += test-fseeko.sh test-fseeko2.sh test-fseeko3.sh test-fseeko4.sh
+check_PROGRAMS += test-fseeko test-fseeko3 test-fseeko4

new file mode 100644
--- /dev/null
+++ b/tests/test-fseeko4.c
@@ -0,0 +1,71 @@
+/* Test of fseeko() function.
+   Copyright (C) 2011 Free Software Foundation, Inc.
+
+   This program 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.
+
+   This program 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 <http://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+#include <stdio.h>
+
+#include <errno.h>
+#include <unistd.h>
+
+#include "macros.h"
+
+int
+main (int argc, char **argv)
+{
+  const char *filename = argv[1];
+
+  /* Test that fseeko() sets errno if someone else closes the stream
+     fd behind the back of stdio.  */
+  {
+    FILE *fp = fopen (filename, "r");
+    ASSERT (fp != NULL);
+    setvbuf (fp, NULL, _IONBF, 0);
+    ASSERT (ftell (fp) == 0);
+    ASSERT (fseeko (fp, 0, SEEK_END) == 0);
+    ASSERT (ftell (fp) > 0);
+    ASSERT (close (fileno (fp)) == 0);
+    errno = 0;
+    ASSERT (fseeko (fp, 0, SEEK_SET) == -1);
+    ASSERT (errno == EBADF);
+    fclose (fp);
+  }
+
+  /* Test that fseeko() sets errno if the stream was constructed with
+     an invalid file descriptor.  */
+  {
+    FILE *fp = fdopen (-1, "w");
+    if (fp != NULL)
+      {
+        errno = 0;
+        ASSERT (fseeko (fp, 0, SEEK_END) == -1);
+        ASSERT (errno == EBADF);
+        fclose (fp);
+      }
+  }
+  {
+    FILE *fp = fdopen (99, "w");
+    if (fp != NULL)
+      {
+        errno = 0;
+        ASSERT (fseeko (fp, 0, SEEK_END) == -1);
+        ASSERT (errno == EBADF);
+        fclose (fp);
+      }
+  }
+
+  return 0;
+}

new file mode 100755
--- /dev/null
+++ b/tests/test-fseeko4.sh
@@ -0,0 +1,5 @@
+#!/bin/sh
+
+./test-fseeko4${EXEEXT} "$srcdir/test-fseeko4.sh" || exit 1
+
+exit 0