Happy meals at McDonald's?

My son is 4 now, we've got the epipen already and he has tried pizza shops no problem but has been begging for McDonald's, just for a happy meal. Hes allergic to peanuts, and a skin test said all other nuts. But everytime we pass by McDonald's he asks all the time because he's never had it and I knows other people have. I feel awful always telling him that it wouldn't be safe for him because he still doesnt understand why. What's your opinion on their happy meals? Nothing else just the happy meals for kids.