For the second time in recent weeks, Stevie Nicks [ tickets ] has postponed a pair of concerts due to illness. The postponements come just as make-up dates have been confirmed for two shows that the singer postponed late last month.

Nicks’ Tuesday and Wednesday night (8/14,15) concerts in Mountain View and Concord, Calif., respectively, have been postponed due to an unspecified illness. Both are expected to be rescheduled soon, according to Nicks’ official website. Ticketholders will be able to use their tickets at the to-be-scheduled make-up dates, or can obtain refunds at the point of purchase, according to venue officials.

Last month, Nicks postponed performances in Virginia and North Carolina due to illness as well. Those shows, originally scheduled for late July, will be made up on Sept. 4 and 5.

A spokesperson for Nicks could not be reached for comment on the nature of the singer’s illness. Nicks is expected to resume touring on Friday night (8/17) in Santa Barbara, Calif.

In addition to the make-up dates, Nicks has also added a batch of new September dates to her outing in support of this year’s “Trouble in Shangri-La” (Reprise). Tickets for a number of shows go on sale in the coming days. Details appear in the itinerary below.

“Trouble in Shangri-La,” Nicks’ first collection of all-new material in almost seven years, hit stores in May.