Preheat the oven to 350. In a medium bowl, toss together the peaches, sugar, flour, and pinch of salt. Spread the mixture in the bottom of a 9 x 9 baking dish.
In another medium bowl, whisk together the oats, flour, brown sugar, cinnamon, and salt. Grate in the butter, and smush the mixture with your fingers until the pieces of butter are no larger than pea sized. Sprinkle the topping over the fruit to form an even layer.
Bake 40-45 minutes, or until golden brown on top and bubbling. Let cool 10-15 minutes before serving.