WASHINGTON (AP) — Long-term U.S. mortgage rates fell this week, making it slightly more affordable to borrow for a home.

Mortgage buyer Freddie Mac says the average rate on 30-year fixed-rate mortgages slipped to 3.95 percent from 3.99 percent last week. The average has tumbled from 4.20 percent a year ago.

The average rate on 15-year fixed-rate mortgages fell to 3.38 percent from 3.44 percent in the prior week. This same rate average 3.44 percent last year.

The interest charged on U.S. Treasury notes dropped from a week ago, causing mortgage rates to slip in response.

The average on five-year adjustable-rate mortgages slipped to 3.45 percent from 3.47 percent last week.