Merle Haggard has again canceled a series of tour dates as he continues to recover from the double pneumonia he has been battling since December.

The 78-year-old Country Music Hall of Fame member canceled his April appearances after doctors recommended additional rest to complete his recovery.

“I want to thank my fans for their prayers and well wishes,” he said in a statement released Tuesday (March 29). “I hope to be back on the road in May, but I’m taking it one day at a time.”

Haggard has been hospitalized several times since December. He canceled several concerts in early February, but he returned to the stage on Feb. 6 and continued playing selected dates. However, he canceled all of his concerts for the months of March and, now, nine April dates scheduled with Willie Nelson.

Haggard is rescheduling some shows, including two nights he planned to perform earlier this month at Nashville’s Ryman Auditorium. Those shows are now set to take place Sept. 27-28.