ABC is building a bigger "Castle."

The network today picked up nine more episodes of the sophomore drama, which has been slowly finding a following on Monday nights. Twenty-two episodes of the Nathan Fillion-led drama will be produced this season.

ABC's decision comes in the wake of "Castle" scoring season-high ratings last night. So far this season, "Castle" has improved the 10 p.m. Monday slot by 4 percent in adults 18-49. The series also is doing well among DVR homes, gaining 26 percent more adult 18-49 viewers when recorded viewing is counted.