Apparently, my measuring skills and sewing-in-a-straight line skills are not as honed as they should be. The fist time I made the square, I accidentally trimmed it to 12" instead of 13". I tried to reuse the khaki as best I could... seeing that I'd serged it! But at least this square should be big enough. Sorry, Emily! I'm hoping that once it is sewn together with the other squares, you won't notice my slanting seams!