diff -Naur ocaml-3.12.1.orig/otherlibs/win32unix/open.c ocaml-3.12.1/otherlibs/win32unix/open.c
--- ocaml-3.12.1.orig/otherlibs/win32unix/open.c	2008-01-11 20:13:18.000000000 +0400
+++ ocaml-3.12.1/otherlibs/win32unix/open.c	2011-12-12 10:18:41.598484400 +0400
@@ -57,7 +57,7 @@
   attr.bInheritHandle = TRUE;

   h = CreateFile(String_val(path), fileaccess,
-                 FILE_SHARE_READ | FILE_SHARE_WRITE, &attr,
+                 FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE, &attr,
                  filecreate, fileattrib, NULL);
   if (h == INVALID_HANDLE_VALUE) {
     win32_maperr(GetLastError());