Scaling a symbol in Sketch scales all instances of that symbol

Title pretty much says it all, but the problem is simple. Say I have a logo imported from illustrator or whatever. I make it a symbol, and then I use it in one place in my design. Looks great.

But there's trouble - I also want a smaller version of that logo somewhere else in the design.

So, I Insert > Symbol > My Crummy Logo and drag it where I want it to go, and then I scale it down, and blammo, the other instance(s) of the logo has just been shrunk too.

Am I doing something incorrectly? Or is this just completely and totally stupid behavior? Or is this logical behavior and I'm just not grokking it?