diff --git a/sw/lib/ocaml/fp_proc.ml b/sw/lib/ocaml/fp_proc.ml
index 1d7b7be09c8..e7ac6adbeeb 100644
--- a/sw/lib/ocaml/fp_proc.ml
+++ b/sw/lib/ocaml/fp_proc.ml
@@ -71,11 +71,10 @@ let transform_expression = fun env e ->
 let transform_values = fun attribs_not_modified env attribs ->
   List.map
     (fun (a, v) ->
-      let e = parse_expression v in
       let v' =
         if List.mem (String.lowercase a) attribs_not_modified
         then v
-        else transform_expression env e in
+        else transform_expression env (parse_expression v) in
       (a, v'))
     attribs
 
@@ -146,7 +145,7 @@ let transform_stage = fun prefix reroutes env xml ->
               let attribs = transform_values ["wp"; "vmode"] env attribs in
               Xml.Element (tag, attribs, children)
             | "call" | "set" ->
-              let attribs = transform_values [] env attribs in
+              let attribs = transform_values ["var"] env attribs in
               Xml.Element (tag, attribs, children)
             | _ -> failwith (sprintf "Fp_proc: Unexpected tag: '%s'" tag)
         end