diff --git a/block/file-posix.c b/block/file-posix.c
index 66fdb07820..ad3021938b 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -2180,7 +2180,7 @@ static void raw_aio_unplug(BlockDriverState *bs)
 #endif
 }
 
-static int raw_co_flush_to_disk(BlockDriverState *bs)
+static int coroutine_fn raw_co_flush_to_disk(BlockDriverState *bs)
 {
     BDRVRawState *s = bs->opaque;
     RawPosixAIOData acb;