Home buyers beware: The cost of financing the purchase of a new home rose in late September for the first time in nearly two months.

The interest rate on a 30-year fixed mortgage rose to an average of 3.83% from 3.78% in the week ended Sept. 21, according to Freddie Mac. That’s the first increase in seven weeks and reverses a steady drop in rates after they topped 4% in mid-July.