diff --git a/block/block-backend.c b/block/block-backend.c
index ee20ae5f0f..0746be8984 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -2418,7 +2418,7 @@ void blk_unregister_buf(BlockBackend *blk, void *host)
 
 int coroutine_fn blk_co_copy_range(BlockBackend *blk_in, int64_t off_in,
                                    BlockBackend *blk_out, int64_t off_out,
-                                   int bytes, BdrvRequestFlags read_flags,
+                                   int64_t bytes, BdrvRequestFlags read_flags,
                                    BdrvRequestFlags write_flags)
 {
     int r;
diff --git a/include/sysemu/block-backend.h b/include/sysemu/block-backend.h
index 3294d1b07a..9ccf9f1a80 100644
--- a/include/sysemu/block-backend.h
+++ b/include/sysemu/block-backend.h
@@ -270,7 +270,7 @@ void blk_unregister_buf(BlockBackend *blk, void *host);
 
 int coroutine_fn blk_co_copy_range(BlockBackend *blk_in, int64_t off_in,
                                    BlockBackend *blk_out, int64_t off_out,
-                                   int bytes, BdrvRequestFlags read_flags,
+                                   int64_t bytes, BdrvRequestFlags read_flags,
                                    BdrvRequestFlags write_flags);
 
 const BdrvChild *blk_root(BlockBackend *blk);