diff --git a/src/lib/CoAlgFormula.ml b/src/lib/CoAlgFormula.ml
index 0cd32cdb2b8e9458c6d5f191dc25b5f35fffbca9..7ab43461108d5a1391771c41d36d66f18180189d 100644
--- a/src/lib/CoAlgFormula.ml
+++ b/src/lib/CoAlgFormula.ml
@@ -231,20 +231,19 @@ let gensym = Stream.from (fun i -> Some (Printf.sprintf "#gensym%x#" i))
 
 let convertToMu formula =
   let helper formula =
-    let symbol = Stream.next gensym in
     match formula with
     | AF f1 ->
-       MU (symbol, (OR (f1, (AX ("", (VAR symbol))))))
+       MU ("#AF#", (OR (f1, (AX ("", (VAR "#AF#"))))))
     | EF f1 ->
-       MU (symbol, (OR (f1, (EX ("", (VAR symbol))))))
+       MU ("#EF#", (OR (f1, (EX ("", (VAR "#EF#"))))))
     | AG f1 ->
-       NU (symbol, (AND (f1, (AX ("", (VAR symbol))))))
+       NU ("#AG#", (AND (f1, (AX ("", (VAR "#AG#"))))))
     | EG f1 ->
-       NU (symbol, (AND (f1, (EX ("", (VAR symbol))))))
+       NU ("#EG#", (AND (f1, (EX ("", (VAR "#EG#"))))))
     | AU (f1, f2) ->
-       MU (symbol, (OR (f2, (AND (f1, (AX ("", (VAR symbol))))))))
+       MU ("#AU#", (OR (f2, (AND (f1, (AX ("", (VAR "#AU#"))))))))
     | EU (f1, f2) ->
-       MU (symbol, (OR (f2, (AND (f1, (EX ("", (VAR symbol))))))))
+       MU ("#EU#", (OR (f2, (AND (f1, (EX ("", (VAR "#EU#"))))))))
     | _ -> formula
   in
   convert_post helper formula