diff --git a/block-migration.c b/block-migration.c
index 7d04d6d..7337349 100644
--- a/block-migration.c
+++ b/block-migration.c
@@ -236,7 +236,7 @@
     BlkMigDevState *bmds;
     int64_t sectors;
 
-    if (bs->type == BDRV_TYPE_HD) {
+    if (!bdrv_is_read_only(bs)) {
         sectors = bdrv_getlength(bs) >> BDRV_SECTOR_BITS;
         if (sectors == 0) {
             return;