Quick Question about function prototypes

Alright, I'm just getting back into C++ after a .5 year break, and I can't quite remeber if this is a problem or not: Suppose I have a class as such...

class myClass
{
void F1(void);
void F2(int x);
void F3(void);
};

Now if, the function F1 calls the function F3, does F3's prototype need to be abot F1's? Cheers