diff --git a/winsup/cygwin/ChangeLog b/winsup/cygwin/ChangeLog
index 8f96fbaaa..3f329ed79 100644
--- a/winsup/cygwin/ChangeLog
+++ b/winsup/cygwin/ChangeLog
@@ -1,3 +1,9 @@
+2003-12-03  Corinna Vinschen  <corinna@vinschen.de>
+
+	* fhandler_disk_file.cc (fhandler_disk_file::lock): Use UINT32_MAX
+	instead of 0xffffffff.  Accomodate Win 9x bug in evaluating length
+	of area to lock when given length is 0.
+
 2003-12-03  Pierre Humblet <pierre.humblet@ieee.org>
 
 	* fhandler_disk_file.cc (fhandler_disk_file::lock): Interchange
diff --git a/winsup/cygwin/fhandler_disk_file.cc b/winsup/cygwin/fhandler_disk_file.cc
index 2c8829ca4..d2adac66d 100644
--- a/winsup/cygwin/fhandler_disk_file.cc
+++ b/winsup/cygwin/fhandler_disk_file.cc
@@ -536,18 +536,21 @@ fhandler_disk_file::lock (int cmd, struct __flock64 *fl)
 
   DWORD off_high, off_low, len_high, len_low;
 
-  off_low = (DWORD)(win32_start & 0xffffffff);
+  off_low = (DWORD)(win32_start & UINT32_MAX);
   off_high = (DWORD)(win32_start >> 32);
   if (win32_len == 0)
     {
       /* Special case if len == 0 for POSIX means lock to the end of
          the entire file (and all future extensions).  */
-      len_low = 0xffffffff;
+      /* CV, 2003-12-03: And yet another Win 9x bugginess.  For some reason
+	 offset + length must be <= 0x100000000.  I'm using 0xffffffff as
+	 upper border here, this should be sufficient. */
+      len_low = UINT32_MAX - (wincap.lock_file_highword () ? 0 : off_low);
       len_high = wincap.lock_file_highword ();
     }
   else
     {
-      len_low = (DWORD)(win32_len & 0xffffffff);
+      len_low = (DWORD)(win32_len & UINT32_MAX);
       len_high = (DWORD)(win32_len >> 32);
     }