Antialiasing shapes in Pygame

I’m using Pygame to draw some things. The problem is that they have a lot of aliased edges: I want to make them softer, like this: My idea so far was to draw the shape in double size, and then use to shrink it to the size I want. Unfortunately if I’m drawing my shapes on a transparent surface, the smoothscale turns the edges that were touching transparent pixels black! How do I smoothscale a picture without turning alpha-transparent pixels into black, or How else do I antialias edges? Answer In order to draw antialiased filled shapes with pygame, use