Preheat the oven to 350 degrees F (175 degrees C).
Arrange sliced peaches evenly in an 8x8-inch baking dish.
Mix flour, brown sugar, butter, cinnamon, and salt in a bowl using a pastry cutter until crumbly.
Fold oats into flour mixture.
Sprinkle mixture evenly over peaches, pressing down lightly.
Bake in the preheated oven until crispy and golden brown on top, about 30 minutes.