diff --git a/lib/format/ataraid/pdc.c.raid10_failure b/lib/format/ataraid/pdc.c
index b0bb652..8b14d71 100644
--- a/lib/format/ataraid/pdc.c
+++ b/lib/format/ataraid/pdc.c
@@ -490,7 +490,9 @@ devices(struct raid_dev *rd, void *context)
if (context && pdc->raid.type != PDC_T_SPAN)
*((uint64_t *) context) += rd->sectors;
- return pdc->raid.total_disks;
+ return is_raid10(pdc) ?
+ pdc->raid.total_disks / 2 :
+ pdc->raid.total_disks;
}
static int