Index: uspace/app/mkmfs/mkmfs.c
===================================================================
--- uspace/app/mkmfs/mkmfs.c	(revision cdc3afaf697503234a75137371d2e29fba5f79a9)
+++ uspace/app/mkmfs/mkmfs.c	(revision 671b5465f603d36fcb7a767de9a968fd32b0076b)
@@ -649,5 +649,5 @@
 		mark_bmap(ibmap_buf, i, FREE);
 
-	for (i = 2; i < sb->n_zones; ++i)
+	for (i = 2; i < sb->n_zones - sb->first_data_zone; ++i)
 		mark_bmap(zbmap_buf, i, FREE);