diff --git a/block.c b/block.c
index 5f979bd..0d5bee0 100644
--- a/block.c
+++ b/block.c
@@ -1013,7 +1013,7 @@
     buf = g_malloc(COMMIT_BUF_SECTORS * BDRV_SECTOR_SIZE);
 
     for (sector = 0; sector < total_sectors; sector += n) {
-        if (drv->bdrv_is_allocated(bs, sector, COMMIT_BUF_SECTORS, &n)) {
+        if (bdrv_is_allocated(bs, sector, COMMIT_BUF_SECTORS, &n)) {
 
             if (bdrv_read(bs, sector, buf, n) != 0) {
                 ret = -EIO;