diff --git a/block.c b/block.c
index bc85f46..9b0fae5 100644
--- a/block.c
+++ b/block.c
@@ -631,9 +631,10 @@
  * Helper function for bdrv_create_file_fallback(): Zero the first
  * sector to remove any potentially pre-existing image header.
  */
-static int create_file_fallback_zero_first_sector(BlockBackend *blk,
-                                                  int64_t current_size,
-                                                  Error **errp)
+static int coroutine_fn
+create_file_fallback_zero_first_sector(BlockBackend *blk,
+                                       int64_t current_size,
+                                       Error **errp)
 {
     int64_t bytes_to_clear;
     int ret;