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