Java Warning using Vectors: unchecked call to add(E)

Offending bit of code

Vector moves = new Vector();

moves.add(new Integer(x));

Error:

ConnectFour.java:82: warning: [unchecked] unchecked call to add(E) as a member of the raw type java.util.Vector moves.add(new Integer(x));

Not really sure how much info is needed for an error like this....