Gas prices across the US have fallen below $4 a gallon for the first time in more than five months.

The national average price for regular gasoline dropped to $3.999 per gallon Thursday, according to the American Automobile Association, down nearly 3 cents from the previous day.

The drop in gas prices comes as the Strait of Hormuz is set to reopen under a memorandum of understanding between the US and Iran aimed at ending the conflict that disrupted global oil supplies.

It marks the first time the US national average gas price has fallen below $4 since March 30.

GasBuddy reported the national average at about $3.98 early Thursday after prices dipped below the $4 mark on Sunday.

Indiana has the lowest statewide average at $3.40 a gallon and is among 28 states where average gas prices are now below $4.

President Trump signed the US-Iran memorandum of understanding on Wednesday over dinner at the Palace of Versailles in France.

Iran’s closure of the key shipping route in late February cut off roughly 20% of the world’s oil supply, sending crude oil and gasoline prices sharply higher.

Gas prices climbed above $4 nationwide in late March after most shipping through the strait was blocked.

The national average peaked at $4.56 a gallon on May 21 before beginning a steady decline as expectations grew that negotiations would lead to the waterway reopening.

Americans have spent about $46 billion more on gasoline since the start of the conflict, Patrick De Haan, GasBuddy’s head of petroleum analysis, said earlier this week, according to Reuters.