Girls' toilet?

E needed a toilet break and as usual, I took him to the ladies' but this time, he paused.

E " Mummy, why are you taking me to the girls' toilet? I am a boy. The boy's toilet is over there"

Me " Err...because I cant go to the boys' toilet...." (hoping that he would not probe further)

E" then I can go to the girls' toilet?"

Me" for now yes, not when you are older and can manage on your own"