diff --git a/block/vmdk.c b/block/vmdk.c
index fd94b8f605de7c3d706434879ad465b7e6a765d2..1c5e2ef1b3852d726607aba225365ff774e68a56 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -523,7 +523,7 @@ static int vmdk_open_vmfs_sparse(BlockDriverState *bs,
     }
     ret = vmdk_add_extent(bs, file, false,
                           le32_to_cpu(header.disk_sectors),
-                          le32_to_cpu(header.l1dir_offset) << 9,
+                          (int64_t)le32_to_cpu(header.l1dir_offset) << 9,
                           0,
                           le32_to_cpu(header.l1dir_size),
                           4096,