Q:

Void pointer to access structs in char array

I have a buffer, essentially an char array, filled with multiple different structs.  The structs needs to be passed in a buffer like this because it is something I read/write to a socket.  The structs are one header struct and possibly "multiple payload" structs. 
Just to illustrate, it looks like this:
unsigned char buffer[buflen];
struct header *head;
struct payload1 *p1;
struct payload2 *p2;

etc...

Now, when I try to fill this buffer, or retrieve from this buffer, I've used a void *ptr where it is first initialized at the position of the buffer then later at the position after the header, like this:
void *ptr;

ptr = &buffer;
ptr += sizeof(header);

This actually works fine - i.e. the pointer points to the correct memory location and I can retrieve (or insert) a new payload struct just fine, but it does however generate a warning in gcc.  warning: pointer of type ‘void *’ used in arithmetic. 
What can I do to avoid this warning in this case? 

A:

Use char * instead of a void *.  The problem is it's not obvious what incrementing a void * is supposed to do.  I'd expect this to be an error rather than a warning.