WASHINGTON (AP) — Long-term U.S. rates slipped this week, reversing two straight weekly increases.

Mortgage buyer Freddie Mac says the average rate on 30-year, fixed-rate mortgages fell to 3.88 percent from 3.91 percent last week. A year ago, the benchmark rate stood at 3.52 percent.

The rate on 15-year, fixed-rate mortgages, popular with homeowners who are refinancing, dipped to 3.19 percent from 3.21 percent last week. A year ago, the 15-year rate was 2.79 percent.

Long-term home loan rates tend to track the yield on 10-year U.S. Treasury notes, which fell this week.

The average rate on five-year adjustable-rate home loans rose to 3.17 percent this week from 3.16 percent last week and 2.85 percent a year ago.

The Federal Reserve, citing an improved outlook for the U.S. economy, has raised short-term interest rates twice this year and is expected to raise them again at its December meeting.

To calculate average mortgage rates, Freddie Mac surveys lenders across the country between Monday and Wednesday each week. The average doesn't include extra fees, known as points, which most borrowers must pay to get the lowest rates. One point equals 1 percent of the loan amount.

The average fee for a 30-year mortgage was unchanged from last week at 0.5 point. The fee on 15-year loans also remained at 0.5 point.

The fee on adjustable five-year loans stayed at 0.4 point.