Nvidia CEO Jensen Huang on Thursday walked back comments he made in January, when he cast doubt on whether useful quantum computers would hit the market in the next 15 years.

Nvidia has benefited from the rise of quantum, as research on this type of computer is done through simulators on powerful devices like what the company sells. The company is working on making technology to integrate graphics processing units — known in short as GPUs — with chips for quantum computing.

Nvidia CEO Jensen Huang tried to fix a mess he started. It didn’t work. His attempt to walk back his old comments about quantum computing ended up dragging down the same stocks he wanted to help.