diff --git a/src/port/dirmod.c b/src/port/dirmod.c
new file mode 100644
index eac59bd..4dba35a
*** a/src/port/dirmod.c
--- b/src/port/dirmod.c
*************** pgrename(const char *from, const char *t
*** 57,69 ****
  	 * and blocking other backends.
  	 */
  #if defined(WIN32) && !defined(__CYGWIN__)
! 	while (!MoveFileEx(from, to, MOVEFILE_REPLACE_EXISTING))
  #else
  	while (rename(from, to) < 0)
- #endif
  	{
  #if defined(WIN32) && !defined(__CYGWIN__)
! 		DWORD		err = GetLastError();
  
  		_dosmaperr(err);
  
--- 57,95 ----
  	 * and blocking other backends.
  	 */
  #if defined(WIN32) && !defined(__CYGWIN__)
! 	DWORD		err;
! 
! 	/*
! 	 * On Windows we use ReplaceFile() to rename while concurrent processes
! 	 * have file open.  However, ReplaceFile() is to be used only when target
! 	 * file is already exists.  Thus, we check for file existence and then
! 	 * choose between MoveFileEx() and ReplaceFile() functions.
! 	 */
! 	while (true)
! 	{
! 		DWORD		dwAttrib;
! 		bool		filePresent;
! 
! 		dwAttrib = GetFileAttributes(to);
! 		filePresent = (dwAttrib != INVALID_FILE_ATTRIBUTES) &&
! 					 !(dwAttrib & FILE_ATTRIBUTE_DIRECTORY);
! 
! 		if (filePresent)
! 		{
! 			if (ReplaceFile(to, from, NULL, REPLACEFILE_IGNORE_MERGE_ERRORS, 0, 0))
! 				break;
! 		}
! 		else
! 		{
! 			if (MoveFileEx(from, to, MOVEFILE_REPLACE_EXISTING))
! 				break;
! 		}
  #else
  	while (rename(from, to) < 0)
  	{
+ #endif
  #if defined(WIN32) && !defined(__CYGWIN__)
! 		err = GetLastError();
  
  		_dosmaperr(err);