Priority Queue Comparison

I'm trying to declare a priority queue in c++ using a custom comparison function...

So , I declare the queue as follows:

std::priority_queue<int,std::vector<int>, compare> pq;

and here's the compare function :

bool compare(int a, int b)
{
   return (a<b);
}

I'm pretty sure I did this before, without a class,in a similar way, but now, this code doesn't compile and I get several errors like this :

type/value mismatch at argument 3 in template parameter list for 'template<class _Tp, class _Sequence, class _Compare> class std::priority_queue'

Is there a way to create a compare function similar to this but without using a class?

Thanks