diff --git a/hw/s390x/css.c b/hw/s390x/css.c
index aa61773885..9e98f50868 100644
--- a/hw/s390x/css.c
+++ b/hw/s390x/css.c
@@ -524,6 +524,7 @@ static void sch_handle_start_func(SubchDev *sch, ORB *orb)
             return;
         }
         sch->ccw_fmt_1 = !!(orb->ctrl0 & ORB_CTRL0_MASK_FMT);
+        s->flags |= (sch->ccw_fmt_1) ? SCSW_FLAGS_MASK_FMT : 0;
         sch->ccw_no_data_cnt = 0;
         suspend_allowed = !!(orb->ctrl0 & ORB_CTRL0_MASK_SPND);
     } else {