diff --git a/include/sysemu/block-backend.h b/include/sysemu/block-backend.h
index b5409a6b45..3fbc74e17c 100644
--- a/include/sysemu/block-backend.h
+++ b/include/sysemu/block-backend.h
@@ -183,7 +183,7 @@ BlockAIOCB *blk_aio_ioctl(BlockBackend *blk, unsigned long int req, void *buf,
                           BlockCompletionFunc *cb, void *opaque);
 int coroutine_fn blk_co_pdiscard(BlockBackend *blk, int64_t offset,
                                  int64_t bytes);
-int blk_co_flush(BlockBackend *blk);
+int coroutine_fn blk_co_flush(BlockBackend *blk);
 int blk_flush(BlockBackend *blk);
 int blk_commit_all(void);
 void blk_inc_in_flight(BlockBackend *blk);