Collections.sort() and Generics?

[<ABX]

I'm getting a warning when calling collections.sort() when passing an ArrayList
containing instances of subclasses of an abstract class.

import java.lang.Comparable;

public abstract class Person<V extends Comparable> implements Comparable<V>  {

	public String name = "";
	public int age = 0;

	public Person() {

	}

	public int compareTo(V o) {
		return this.age - o.age;
	}

} // Person

public class Drunk extends Person {

	public double BAC = 0;

	public Drunk() {
		super();
	}

} // Drunk

import java.lang.Comparable;
import java.util.ArrayList;
import java.util.Collections;


public class GenericsTest {

	public static void main(String[] args) {

		ArrayList<Person> ppl = new ArrayList<Person>();

		Drunk myDrunk1 = new Drunk();

		Drunk myDrunk2 = new Drunk();


		ppl.add(myDrunk1);
		ppl.add(myDrunk2);

		Collections.sort(ppl);
	}

} // GenericsTest

Produces the warning: warning: [unchecked] unchecked method invocation: <T>sort(java.util.List<T>) in java.util.Collections is applied to (java.util.ArrayList<Person>)
Collections.sort(ppl);
^

I think there is something wrong with the way I'm declaring the abstract class Person.