The next Studio Ghibli film from formerly retired director Hayao Miyazaki isn’t likely to meet its previously announced 2019 release date, according to the film’s producer.

Toshio Suzuki spoke at the Niconico Chōkaigi convention this past weekend about Miyazaki’s next project, which is based on the short film Kemushi no Boro (Boro the Caterpillar). Despite the enormous amount of work Miyazaki is putting into the project, Suzuki said there’s only about 20 minutes of storyboarding done, as reported by Huffington Post Japan. Suzuki added that Miyazaki has been hard at work on the project since last July, but it’s taking more time than usual.

The short film will debut at the Ghibli Museum in Tokyo this July, but Suzuki was adamant the feature version of the film couldn’t meet the earlier proposed 2019 release date. When asked by a local reporter if Miyazaki could finish the film in his lifetime, Suzuki admitted that he wasn’t sure.

Miyazaki and Ghibli confirmed in February that they were moving ahead with the project after the director teased it late last year. In a documentary called Hayao Miyazaki: The Man Who Is Not Done, Miyazaki admitted he wasn’t happy with the way the short film turned out. The director added that it he could get the financial backing of a studio like Ghibli, he would turn it into a feature film.

Kemushi no Boro does not have a release date and Suzuki didn’t hint at when fans should expect it, but it’s probably not going to be for another few years.