It wasn’t a fluke: Researchers at a Department of Energy lab have repeated their breakthrough fusion power experiment. Only this time, the results are even better.

On July 30, lasers once again converged on a tiny gold cylinder containing a diamond-coated, deuterium-tritium fuel pellet. When the beams — as many as 192 of them — hit the inside of the cylinder, their energy was turned into X-rays. Those X-rays then bombarded the fuel pellet, forcing it to implode.

Last time, the resulting nuclear fusion reaction released 3.15 megajoules of energy. This time, it produced more than 3.5 megajoules, according to the Financial Times. That reportedly exceeds the amount of energy the lasers imparted on the hohlraum, as the cylinder is called, though it’s unclear by how much.

The lab confirmed the successful repetition of the experiment and said it intends to report the details at either a scientific conference or in a peer-reviewed publication (likely both).

While the most recent experiment won’t garner quite as many headlines as the one in December, it’s just as important. A breakthrough is meaningless if it can’t be replicated. The fact that scientists have achieved net-positive fusion power twice should hearten investors, who bet over $4 billion on the industry in 2021 and 2022.

Perhaps most encouraging is the fact that the July 30 shot didn’t simply repeat the December results, it improved on them. We still don’t know what the scientists did to better their numbers, but the bump in energy-out suggests that the new results are not a fluke. Scientists are probably getting better at understanding the quirks of inertial confinement fusion.