diff --git a/winsup/testsuite/ChangeLog b/winsup/testsuite/ChangeLog
index f2922ef1c..0aa4f837e 100644
--- a/winsup/testsuite/ChangeLog
+++ b/winsup/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2001-04-03  Corinna Vinschen  <corinna@vinschen.de>
+
+	* winsup.api/mmaptest01.c: New test.
+
 2001-03-10  Egor Duda  <deo@logos-m.ru>
 
 	* winsup.api/ltp/access01.c: Avoid compilation error if X_OK
diff --git a/winsup/testsuite/winsup.api/mmaptest01.c b/winsup/testsuite/winsup.api/mmaptest01.c
new file mode 100644
index 000000000..b400db7f4
--- /dev/null
+++ b/winsup/testsuite/winsup.api/mmaptest01.c
@@ -0,0 +1,106 @@
+/*
+  Copyright 2001 Free Software Foundation, Inc.
+  Written by Michael Chastain, <chastain@redhat.com>
+
+  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 2 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, write to the Free Software
+  Foundation, Inc., 59 Temple Place - Suite 330,
+  Boston, MA 02111-1307, USA.
+
+  This program demonstrates a bug in cygwin's mmap.
+  I open one file, mmap it, and close it.
+  I open a different file, mmap it, and close it.
+
+  The second file re-uses the file handle (which is OK),
+  but then it re-uses the buffer as well!  Ouch!
+
+  This bug occurs on cygwin1.dll dated 2001-01-31.
+  It causes gnu cpp to screw up its include file buffers.
+
+  Compile with "gcc -o y1 y1.c".
+
+  Output from a bad cygwin1.dll:
+
+    y1.txt: 3 0x4660000 y1 y1 y1 y1 y1 y1 y1
+    y2.txt: 3 0x4660000 y1 y1 y1 y1 y1 y1 y1
+
+  Output from a good cygwin1.dll:
+
+    y1.txt: 3 0x14060000 y1 y1 y1 y1 y1 y1 y1
+    y2.txt: 3 0x14070000 y2 y2 y2 y2 y2 y2 y2
+
+  Output from Red Hat Linux 7:
+
+    y1.txt: 3 0x40017000 y1 y1 y1 y1 y1 y1 y1
+    y2.txt: 3 0x40018000 y2 y2 y2 y2 y2 y2 y2
+ */
+
+#include <sys/mman.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+/* some systems have O_BINARY and some do not */
+#ifndef O_BINARY
+#define O_BINARY 0
+#endif
+
+/* filler for file 1 */
+char const line1 [] = "y1 y1 y1 y1 y1 y1 y1 y1 y1 y1 y1 y1 y1 y1 y1 y1 y1\n";
+#define size1 (sizeof(line1) - 1)
+#define count1 ((4096 / size1) + 1)
+
+/* filler for file 2 */
+char const line2 [] = "y2 y2 y2 y2 y2 y2 y2 y2 y2 y2 y2 y2 y2 y2 y2 y2 y2\n";
+#define size2 (sizeof(line2) - 1)
+#define count2 ((4096 / size2) + 1)
+
+int main ()
+{
+  int fd1;
+  char * buf1;
+
+  int fd2;
+  char * buf2;
+
+  int i;
+
+  /* create file 1 */
+  fd1  = open ("y1.txt", O_WRONLY|O_CREAT|O_TRUNC|O_BINARY, 0644);
+  for (i = 0; i < count1; i++)
+    write (fd1, line1, size1);
+  close (fd1);
+
+  /* create file 2 */
+  fd2  = open ("y2.txt", O_WRONLY|O_CREAT|O_TRUNC|O_BINARY, 0644);
+  for (i = 0; i < count2; i++)
+    write (fd2, line2, size2);
+  close (fd2);
+
+  /* mmap file 1 */
+  fd1  = open ("y1.txt", O_RDONLY | O_BINARY, 0644);
+  buf1 = mmap (0, 4096, PROT_READ, MAP_PRIVATE, fd1, 0);
+  close (fd1);
+
+  /* mmap file 2 */
+  fd2  = open ("y2.txt", O_RDONLY | O_BINARY, 0644);
+  buf2 = mmap (0, 4096, PROT_READ, MAP_PRIVATE, fd2, 0);
+  close (fd2);
+
+  /* the buffers have to be different */
+  if (buf1 == buf2 || !memcmp (buf1, buf2, 20))
+    return 1;
+
+  return 0;
+}
+