Type Promotion in function call

I have not compiled this just looking for advice:

Code:

---

unsigned functionFoo()
{
        unsigned fooNum = 0;
        //...
       
        return fooNum;
}

void functionBar(unsigned long myNum)
{
        //..
}

int main()
{
        unsigned num = functionFoo();
        functionBar(num);
       
        return 0;
}

---

So is this safe? Its is for a random number generator, so i would like to be sure everything is tickety-boo, it's using Prelude's mersenne twister implementation, the seed function takes the unsigned long int, but prior to that i am using a seperate time_t hash function that returns the unsigned int

It's safe in that conversion from unsigned int -> unsigned long is guaranteed to be lossless. It may be unsafe in that it may make the outcome of the rng more predictable than necessary (if long is actually larger than int, you're not using the full range of the seed), but that's unlikely to be a serious problem.