diff --git a/src/low_level.ml b/src/low_level.ml
index d07e56a..8efe655 100644
--- a/src/low_level.ml
+++ b/src/low_level.ml
@@ -688,7 +688,7 @@ let readv fd bufs =
             end)
           bufs;
         r := File { e with pos = !pos }
-    | r -> Fmt.failwith "TODO: readv %a" Resource.pp r
+    | r -> Fmt.failwith "Cannot perform readv on: %a" Resource.pp r
   in
   (!read, fds)