Maybe the belt just needs to be adjusted or tightened. Belts stretch and get a little lose over time, if you cannot adjust it anymore, you can put some soap (dry) on the belt. It will stop the squeak for a few weeks.
Unfortunatly due to the adverse cold weather were having at the moment it doesnt help......on the other hand my alternator is about to pack in ,,,,car starts with a jump , also my battery has a full charge :( relegated to driving the old mans volvo 940 over the holidays :(