diff --git a/src/plugins/wp/Vset.ml b/src/plugins/wp/Vset.ml
index a5b1b571e3df6d50cbff9bf1a756130c8871c377..87bb24efac6a1936206c80b2395156d5529391ef 100644
--- a/src/plugins/wp/Vset.ml
+++ b/src/plugins/wp/Vset.ml
@@ -110,7 +110,7 @@ let typecheck_singleton (params:tau option list) : tau =
 let typecheck_range (_:tau option list) : tau =
   tau_of_set Logic.Int
 
-let p_member = Lang.extern_p ~library ~bool:"member_bool" ~prop:"mem" ()
+let p_member = Lang.extern_p ~library ~bool:"memb" ~prop:"mem" ()
 let f_empty = Lang.extern_f ~library "empty"
 let f_union = Lang.extern_f ~library ~typecheck:typecheck_binop "union"
 let f_inter = Lang.extern_f ~library ~typecheck:typecheck_binop "inter"
diff --git a/src/plugins/wp/share/why3/frama_c_wp/vset.mlw b/src/plugins/wp/share/why3/frama_c_wp/vset.mlw
index 88ec3a1db1a86047f12852c9aa2b42c94505961f..db63c2110a213c95139c7db30f8b169b3c522b58 100644
--- a/src/plugins/wp/share/why3/frama_c_wp/vset.mlw
+++ b/src/plugins/wp/share/why3/frama_c_wp/vset.mlw
@@ -21,32 +21,27 @@
 (**************************************************************************)
 
 (* -------------------------------------------------------------------------- *)
-(* --- Sets for Why-3                                                     --- *)
+(* --- Additional Sets Symbols for WP                                     --- *)
 (* -------------------------------------------------------------------------- *)
 
 theory Vset
 
-  use bool.Bool
   use int.Int
-  use map.Map
+  use map.Const
   use export set.Set
 
-  (* -------------------------------------------------------------------------- *)
-  (* --- Classical Sets for Alt-Ergo                                        --- *)
-  (* -------------------------------------------------------------------------- *)
-
-  function member_bool (x:'a) (s:set 'a) : bool = s x
+  function memb (x:'a) (s:set 'a) : bool = s x
 
   let function range (inf sup:int) : set int (* [a..b] *) =
-    fun elt -> if inf <= elt <= sup then true else false
+    fun elt -> inf <= elt <= sup
 
   function range_sup (sup:int) : set int (* [a..] *) =
-    fun elt -> if elt <= sup then true else false
+    fun elt -> elt <= sup
 
   function range_inf (inf:int) : set int (* [..b] *) =
-    fun elt -> if inf <= elt then true else false
+    fun elt -> inf <= elt
 
-  function range_all : set int (* [..] *) = fun _ -> true
+  function range_all : set int (* [..] *) = const true
 
   (* -------------------------------------------------------------------------- *)