diff --git a/test/kcas_data/queue_test_stm.ml b/test/kcas_data/queue_test_stm.ml
index d3b0174e..e3c41695 100644
--- a/test/kcas_data/queue_test_stm.ml
+++ b/test/kcas_data/queue_test_stm.ml
@@ -30,8 +30,7 @@ module Spec = struct
     [
       Gen.int |> Gen.map (fun x -> Push x);
       Gen.return Take_opt;
-      Gen.return Peek_opt;
-      Gen.return Length;
+      Gen.return Length |> Gen.map (fun _ -> Peek_opt);
     ]
     |> Gen.oneof |> make ~print:show_cmd