About transforms.Normalize channel

About 6 months ago, I used this transforms for MNIST datasets and It had been worked well.

normalize = transforms.Normalize(mean=[0.5, 0.5, 0.5],
                                 std=[0.5, 0.5, 0.5])

But now, above code have error, because MNIST have channel only 1 I think.
So I changed above codes to this. and It works.

normalize = transforms.Normalize(mean=[0.5],

Is there any update pytorch? or something I missing?