diff --git a/block.c b/block.c
index 6a95768..0b0966c 100644
--- a/block.c
+++ b/block.c
@@ -361,6 +361,10 @@ static int refresh_total_sectors(BlockDriverState *bs, int64_t hint)
 {
     BlockDriver *drv = bs->drv;
 
+    /* Do not attempt drv->bdrv_getlength() on scsi-generic devices */
+    if (bs->sg)
+        return 0;
+
     /* query actual device if possible, otherwise just trust the hint */
     if (drv->bdrv_getlength) {
         int64_t length = drv->bdrv_getlength(bs);