diff --git a/libisofs/ecma119.c b/libisofs/ecma119.c
index b33793f..7f94b3b 100644
--- a/libisofs/ecma119.c
+++ b/libisofs/ecma119.c
@@ -2082,6 +2082,9 @@ int ecma119_image_new(IsoImage *src, IsoWriteOpts *opts, Ecma119Image **img)
         goto target_cleanup;
 #endif /* ! Libisofs_gpt_writer_lasT */
 
+
+    /* >>> Should not the checksum writer come before the zero writer ? */
+
     /* IMPORTANT: This must be the last writer before the checksum writer */
     ret = zero_writer_create(target, target->tail_blocks, 1);
     if (ret < 0)
diff --git a/libisofs/system_area.c b/libisofs/system_area.c
index d270c16..3612a25 100644
--- a/libisofs/system_area.c
+++ b/libisofs/system_area.c
@@ -2030,8 +2030,7 @@ static int partprepend_writer_compute_data_blocks(IsoImageWriter *writer)
         t->curblock += t->efi_boot_part_size;
     }
 
-    if ((((t->system_area_options >> 10) & 0xf) == 1) &&
-       ((t->system_area_options >> 2) & 0x3f) == 0) {
+    if ((t->system_area_options & 0x3cff) == 0x0400) {
         /* CHRP is not compatible with any other partition in MBR */
         if (t->prep_partition != NULL || t->fat || will_have_gpt ||
             t->mbr_req_count > 0)