Star Trek: Discovery, CBS’ upcoming addition to the long running sci-fi series, has been delayed again.

The Hollywood Reporter confirmed that the network decided to push back the release date as the show continues to round out its casting. In a statement to the magazine, a CBS representative said while filming on the series begins next week in Toronto, the show will premiere later than expected because of late casting and script changes.

“This is an ambitious project; we will be flexible on a launch date if it's best for the show,” the rep said. “We've said from the beginning it's more important to do this right than to do it fast. There is also added flexibility presenting on CBS All Access, which isn't beholden to seasonal premieres or launch windows.”

Star Trek: Discovery was originally supposed to premiere in early 2017, but was pushed back to May. Producers on the series cited issues with both the script and visual effects that needed to be worked out. Former showrunner Bryan Fuller added that in order to make the best series they could, a delay was necessary.

“We aim to dream big and deliver, and that means making sure the demands of physical and post-production for a show that takes place entirely in space, and the need to meet an air date, don’t result in compromised quality,” Fuller said in a statement.

In October, Fuller stepped down as showrunner, citing scheduling conflicts with other series he was working on, including Starz’s American Gods. CBS was reportedly bothered by Fuller’s inability to devote 100 percent of his time to the series and was concerned about progress on the show following its delay.

In November, CBS announced the first wave of casting for the series. Doug Jones (Pan’s Labyrinth) and Anthony Rapp (Rent) joined Michelle Yeoh, whose involvement was previously reported. Jones will play Lieutenant Saru, while Rapp will take on the role of Lieutenant Stamets. Like previous reports suggested, Yeoh will play Captain Georgiou. CBS confirmed today that James Frain would play Spock’s father.

Star Trek: Discovery, which is set before the events of the original series in 1966, does not have a new premiere date at this time.