U.S. retail sales fell in September by the largest amount in three months, although the weakness primarily reflected a big drop in gasoline prices, which helped to boost spending in other categories.

Overall retail sales decreased by a seasonally adjusted 0.4%, the U.S. Commerce Department said today, compared with a revised 0.1% increase in August. That figure had been previously reported as a 0.2% increase.

Economists had expected overall retail sales to climb 0.3% in September.

The average price of gasoline dropped by US40¢ a gallon in September, which pushed down the value of gas-station receipts. Gas-station sales plunged by a record 9.3%, according to the retail report.

Stripping away sales at gas stations, demand at all other retailers was up 0.6% in September.

Auto and parts retail sales were unchanged in September.

Excluding both autos and gasoline, all other retail sales increased 0.8% in September — the strongest climb since January’s 2.5%.