diff --git a/projects/miragesdk/src/sdk/IO.ml b/projects/miragesdk/src/sdk/IO.ml
index 142583844..7271e8962 100644
--- a/projects/miragesdk/src/sdk/IO.ml
+++ b/projects/miragesdk/src/sdk/IO.ml
@@ -45,8 +45,8 @@ let forward ~src ~dst =
       Log.err (fun l -> l "forward[%a => %a] %a" pp src pp dst pp_error e);
       Lwt.return_unit
     | Ok (`Data buf) ->
-      Log.debug (fun l -> l "forward[%a => %a] @[%S@]"
-                    pp src pp dst @@ Cstruct.to_string buf);
+      Log.debug (fun l -> l "forward[%a => %a] %d bytes"
+                    pp src pp dst @@ Cstruct.len buf);
       write dst buf >>= function
       | Ok ()   -> loop ()
       | Error e ->