diff --git a/model/riscv_insts_fext.sail b/model/riscv_insts_fext.sail
index 3e6b575e3..966338db8 100644
--- a/model/riscv_insts_fext.sail
+++ b/model/riscv_insts_fext.sail
@@ -1061,7 +1061,7 @@ function clause execute (F_UN_TYPE_S(rs1, rd, FCLASS_S)) = {
 }
 
 function clause execute (F_UN_TYPE_S(rs1, rd, FMV_X_W)) = {
-  X(rd) = sign_extend(F(rs1)[31 .. 0]);
+  X(rd) = sign_extend(F(rs1)[31..0]);
   RETIRE_SUCCESS
 }