diff --git a/test/test.ml b/test/test.ml
index dac934bc..bc491f9b 100644
--- a/test/test.ml
+++ b/test/test.ml
@@ -71,3 +71,14 @@ let () =
   check_bad "\"foo\" ,";
   check_bad ", \"foo\"";
   ()
+
+let () =
+  let open Binary_formats.Withdraw_confirmation_ps in
+  let str64 = String.make 64 '0' in
+  let dummy_t =
+    { h_planchets= { hash= { hash= str64 } }; noreveal_index= 0_l }
+  in
+  let size' = Bin.size_of_value bin dummy_t |> Option.get in
+  assert (size = size');
+  assert (size = 76);
+  ()