diff --git a/hosts/ocaml/lib/sx_ref.ml b/hosts/ocaml/lib/sx_ref.ml
index aedf1284..b187a008 100644
--- a/hosts/ocaml/lib/sx_ref.ml
+++ b/hosts/ocaml/lib/sx_ref.ml
@@ -374,11 +374,16 @@ and expand_macro mac raw_args env =
 
 (* cek-run *)
 and cek_run state =
-  (if sx_truthy ((cek_terminal_p (state))) then (cek_value (state)) else
-   try cek_run ((cek_step (state)))
-   with Eval_error msg ->
-     (if !_last_error_kont = Nil then _last_error_kont := cek_kont state);
-     raise (Eval_error msg))
+  (* Iterative loop — no stack growth. Essential for WASM where JS stack is limited. *)
+  let s = ref state in
+  (try
+    while not (match cek_terminal_p !s with Bool true -> true | _ -> false) do
+      s := cek_step !s
+    done;
+    cek_value !s
+  with Eval_error msg ->
+    (if !_last_error_kont = Nil then _last_error_kont := cek_kont !s);
+    raise (Eval_error msg))
 
 (* cek-step *)
 and cek_step state =