1 files changed, 1 insertions, 1 deletions
diff --git a/block.c b/block.c
index f2f8ae7..d7781ee 100644
--- a/block.c
+++ b/block.c
@@ -5452,7 +5452,7 @@ BdrvDirtyBitmap *bdrv_create_dirty_bitmap(BlockDriverState *bs, int granularity,
         return NULL;
     }
     bitmap = g_new0(BdrvDirtyBitmap, 1);
-    bitmap->bitmap = hbitmap_alloc(bitmap_size, ffs(granularity) - 1);
+    bitmap->bitmap = hbitmap_alloc(bitmap_size, ctz32(granularity));
     QLIST_INSERT_HEAD(&bs->dirty_bitmaps, bitmap, list);
     return bitmap;
 }