The CW has ordered an additional four episodes of “DC’s Legends of Tomorrow,” bringing the current Season 2 order to a total of 17 episodes.

In addition to “Legends of Tomorrow,” all the CW superhero shows have full season orders, as “Arrow” and “The Flash” were initially renewed with 23-episode seasons, and when “Supergirl” moved from CBS to CW, the network picked it up for a second season with 22 episodes.

“DC’s Legends” was a midseason show in its freshman season, so it was only ordered with 13 episodes for this fall.

The lowest-rated of the CW’s superhero quartet, “Legends” is a healthy performer for the younger-skewing network, averaging 2.34 million viewers and a 0.9 rating in the 18-49 demo in its second season, including DVR viewership. The show improved the time period from last fall, which was previously slotted with “The Vampire Diaries,” by 13% among adults 18-49 and 35% in total viewers.

The CW still hasn’t made a decision on the future of new fall series “No Tomorrow” and “Frequency.”

Coming up midseason on CW is Greg Berlanti’s newest addition to his foursome with “Riverdale,” plus the returns of “iZombie,” “Reign,” “The Originals,” and the fan-favorite series “The 100.”