DependencyProperty of type System.Double cannot be set on an object of type System.Int32

I have this bit of code:

nextCard.SetValue(Canvas.LeftProperty, 50);

which worked before, but now throws this exception

DependencyProperty of type System.Double cannot be set on an object of type System.Int32

So I've changed it to

nextCard.SetValue(Canvas.LeftProperty, 50d);

And it works.  Any reason for the lack of implicit conversion?  Or is this just something to get used to?

 
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