diff --git a/block.c b/block.c
index 2b9ceae02f..2786e47d1e 100644
--- a/block.c
+++ b/block.c
@@ -3224,6 +3224,7 @@ static void bdrv_dirty_bitmap_truncate(BlockDriverState *bs)
             continue;
         }
         hbitmap_truncate(bitmap->bitmap, size);
+        bitmap->size = size;
     }
 }