diff --git a/src/fileio.c b/src/fileio.c
index 12c064cb34a..32deff96a71 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -2350,7 +2350,7 @@ A prefix arg makes KEEP-TIME non-nil.")
 
       /* Ensure file is writable while its modified time is set.  */
       attributes = GetFileAttributes (filename);
-      SetFileAttributes (filename, attributes ^ FILE_ATTRIBUTE_READONLY);
+      SetFileAttributes (filename, attributes & ~FILE_ATTRIBUTE_READONLY);
       if (set_file_times (filename, now, now))
 	{
 	  /* Restore original attributes.  */