Tuna Noodle and Mushroom casserole

1 can Campbell's cream of mushroom soup
1/2 soup can of milk
1 small can of chopped mushrooms
1 small can of tuna
3 cups of egg noodles, cooked and drained

Mix together the soup, milk, mushrooms, and tuna in a small casserole dish.  Stir in the noodles until thoroughly mixed together.  Bake at 400 degrees for 20 minutes.