For the first time in more than 15 years, it’s cheaper to buy a new house than a previously owned dwelling.

The premium for newly built homes vanished last month as low supply fueled price increases in the broader market and erased the discount traditionally associated with older properties.

The median sales price of a previously owned single-family home rose to $334,500 in March, the latest National Association of Realtors data show. Meanwhile, new properties sold for a median $330,800, according to a government report, marking a reversal in the differential for the first time since June 2005.

Prices — which can vary widely each month depending on the composition of properties sold — increased on a year-over-year basis, but the gains were much larger for older houses. That resale prices have risen so sharply reflects a historically low level of properties available: There were 900,000 existing homes for sale last month, down more than 30% from a year ago.

The number of new homes sold and awaiting the start of construction, meanwhile, climbed to the highest level since September 2006. That’s a sign that builders have their work cut out for them as demand far exceeds supply.