diff --git a/cmd/cmount/mount.go b/cmd/cmount/mount.go
index 8c482b53a..647ea33a5 100644
--- a/cmd/cmount/mount.go
+++ b/cmd/cmount/mount.go
@@ -40,6 +40,11 @@ func mountOptions(device string, mountpoint string) (options []string) {
 		"-o", "fsname=" + device,
 		"-o", "subtype=rclone",
 		"-o", fmt.Sprintf("max_readahead=%d", mountlib.MaxReadAhead),
+		// This causes FUSE to supply O_TRUNC with the Open
+		// call which is more efficient for cmount.  However
+		// it does not work with cgofuse on Windows with
+		// WinFSP so cmount must work with or without it.
+		"-o", "atomic_o_trunc",
 	}
 	if mountlib.DebugFUSE {
 		options = append(options, "-o", "debug")