diff --git a/model/riscv_sys_control.sail b/model/riscv_sys_control.sail
index cf0a488cc..7746b6bcb 100644
--- a/model/riscv_sys_control.sail
+++ b/model/riscv_sys_control.sail
@@ -228,7 +228,7 @@ function check_CSR(csr : csreg, p : Privilege, isWrite : bool) -> bool =
  * where cancellation can be performed.
  */
 
-val speculate_conditional = {ocaml: "Platform.speculate_conditional", interpreter: "excl_res", c: "speculate_conditional", lem: "speculate_conditional_success"} : unit -> bool
+val speculate_conditional = monadic {ocaml: "Platform.speculate_conditional", interpreter: "excl_res", c: "speculate_conditional", lem: "speculate_conditional_success"} : unit -> bool
 
 val load_reservation = {ocaml: "Platform.load_reservation", interpreter: "Platform.load_reservation", c: "load_reservation", lem: "load_reservation"} : xlenbits -> unit
 val match_reservation = {ocaml: "Platform.match_reservation", interpreter: "Platform.match_reservation", lem: "match_reservation", c: "match_reservation"} : xlenbits -> bool